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Cummins/Onan 6BT-5.9-G2 Engine

The Cummins/Onan 6BT-5.9-G2 is a 5.9 L 6-cylinder turbocharged engine rated at 1500 rpm, producing up to 106 kW. It powers generator sets from AKSA and Cummins/Onan, including the ACD 125, 100 DGDB, 65DGDA and 80 DGDA. It holds 16 L (4.2 gal) of oil and 25 L (6.6 gal) of coolant.

Also known as: Cummins 6BT-5.9-G2

Part of the Cummins/Onan 6BT5.9 engine family — 8 variants share parts & fitment.

5.9 L

Displacement

Cylinders

1500 rpm

Rated speed

106 kW

Gross power

On this pageSpecs Generator sets FAQ Service intervals Torque & specs Fluids Fault codes Procedures Wiring

Engine specifications

Oil capacity	16.0 L
Coolant capacity	25.0 L
Displacement	5.9 L
Cylinders	6
Aspiration	Turbocharged
Rated speed	1500 rpm
Gross power	106 kW

Generator sets powered by this engine

Shared across brands: AKSA, Cummins/Onan

AKSA ACD 125 Cummins/Onan 100 DGDB Cummins/Onan 65DGDA Cummins/Onan 80 DGDA Cummins/Onan 95 DGDB Cummins/Onan DGDBCummins/Onan DTDBCummins/Onan DXDB

This engine also powers 2 machine(s) on Power Equipment Info.

How to read your Cummins/Onan engine serial & model number →

Common problems

The FAULT 1 or FAULT 2 fault lamp lights. Engine shuts down immediately, engine runs for several seconds and then shuts down, or engine continues to run FAULT 1
Cause: The standard undesignated fault functions are programmed to shut down the set when a fault is sensed. Fault 1 is time delayed while Fault 2 is immediate. The nature of the fault is an optional selection that is determined when the set installation is designed. The undesignated fault functions may also be programmed for non-shutdown or non-time delay
SWITCH OFF lamp flashes
Cause: Indicates Run/Stop/Remote switch is in the Stop position which will prevent automatic starting if an automatic transfer switch is used
Fix: Move the Run/Stop/Remote switch to the Remote position for automatic starting
LO FUEL LAMP lights. Engine shuts down and LO OIL PRES lamp lights
Cause: Indicates engine has run out of fuel
Fix: Check fuel level and replenish as required
LO FUEL lamp lights. Engine continues to run
Cause: Indicates diesel fuel supply is running low
Fix: Check fuel supply and replenish as required
HI ENG TEMP lamp lights. Engine shuts down
Cause: Indicates engine has overheated (engine temperature has risen above 222°F/106°C) or coolant level is low (sets with coolant level sensor)
Fix: Allow engine to cool down completely before proceeding with the following checks: check coolant level and replenish if low, look for possible coolant leakage points and repair if necessary; check for obstructions to cooling airflow and correct as necessary; check for a slipping fan belt and tighten if loose; reset control and restart after locating and correcting problem; contact an authorized service center for service if none of the above
Fault lamp lights but no fault exists. Engine gauges show oil pressure, engine temperature, and frequency (speed) are within normal limits
Cause: The monitor board or a sensor may be at fault
Fix: Contact an authorized service center for service
Engine will not crank
Cause: Indicates possible fault with control or starting system
Fix: Check for the following conditions: fault lamp on, correct fault and reset control; poor battery cable connections, clean the battery cable terminals and tighten all connections; discharged or defective battery, recharge or replace the battery; emergency stop button (if equipped) pushed in, to reset, pull switch out and move Run/Stop/Remote switch to Stop position, then push test switch to Reset/Lamp position; contact an authorized service center if none of the above
Engine runs and then shuts down, OVERSPEED lamp lights
Cause: Indicates engine has exceeded normal operating speed
Fix: Contact an authorized service center for service
No AC output voltage
Cause: Field breaker is tripped
Fix: Reset breaker; contact an authorized service center if voltage buildup causes breaker to trip
PRE LO OIL PRES lamp lights. Engine continues to operate
Cause: Indicates engine oil pressure has dropped to 20 psi (138 kPa)
Fix: If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow step 5 procedure; if engine can be stopped, follow procedures in step 5
PRE HI ENGINE TEMP lamp lights. Engine continues to operate
Cause: Indicates engine has begun to overheat and engine temperature has risen to approximately 215°F (102°C)
Fix: If generator is powering non-critical and critical loads and cannot be shut down, reduce load if possible by turning off non-critical loads; check air inlets and outlets and remove any obstructions to airflow; if engine can be stopped, follow procedure in step 3
LO OIL PRES lamp lights. Engine shuts down
Cause: Indicates engine oil pressure has dropped to 14 psi (97 kPa)
Fix: Check oil level, lines and filters; if oil system is OK but oil level is low, replenish; reset control and restart; contact an authorized service center if oil pressure is not in the range of 25 to 40 psi (172 to 275 kPa)
LO ENG TEMP lamp lights. Set is in standby mode but is not operating. (Lamp lights when engine coolant temperature is 70°F (21°C) or lower. Since the lamp goes out after the engine warms up, there should be no cause for alarm even during initial generator set operation.)
Cause: Indicates engine coolant heater is not operating or is not circulating coolant
Fix: Check for the following conditions: coolant heater not connected to power supply, check for blown fuse or disconnected heater cord and correct as required; check for low coolant level and replenish if required, look for possible coolant leakage points and repair as required; contact an authorized service center for service if none of the above
Engine starts from generator control panel but will not start automatically or from a remote panel. (Note: The Run/Stop/Remote switch must be in the Remote position for automatic or remote starting)
Cause: Remote circuit breaker is tripped
Fix: Reset breaker and restart; contact an authorized service center if breaker trips after resetting
OVERCRANK lamp lights and engine stops cranking, or engine runs, shuts down, and LO OIL PRES lamp lights
Cause: Indicates possible fuel system problem
Fix: Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required; check for dirty fuel filter and replace if necessary (see Maintenance section); check for dirty or plugged air filter and replace if necessary (see Maintenance section); reset the control and restart after correcting the problem; contact an authorized service center for service if none of the above

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan 6BT-5.9-G2.

Service intervals

Item	Action	Hours	Months	Notes
Coolant Heater	Check	50 hr		Verify hot coolant is being discharged from the outlet hose.
Coolant Level	Check	8 hr
Coolant Level (Recovery Tank)	Check	8 hr		Table 5-1
Exhaust Condensate Trap	Drain	8 hr		Table 5-1
Fuel Level	Check	8 hr		Table 5-1
Fuel Tanks (water and sediment)	Drain	8 hr		Drain 1 cup or more of fuel to remove water and sediment.
General Genset Inspection	Inspect	8 hr		Table 5-1; also indicated for weekly/50 hours (X1, X2)
Inspect Genset	Check	8 hr		Check for oil, fuel, cooling and exhaust system leaks. Check exhaust system audibly and visually with set running and repair any leaks immediately.
Oil Level	Check	8 hr		Table 5-1
Water and Sediment from Fuel Tank	Drain	8 hr		Table 5-1; drain 1 cup or more of fuel to remove water and sediment
Air Cleaner	Clean	50 hr		Table 5-1; X3 perform more often in dusty conditions
Battery Charging System	Check	50 hr		Table 5-1
Charge Air Piping	Check	50 hr		Table 5-1
Crankcase Oil	Drain	50 hr		First service — Break-in: drain and replace the crankcase oil after the first 50 hours of operation on new generator sets.
Crankcase oil	Change	50 hr		First service — Drain and replace the crankcase oil after the first 50 hours of operation on new generator sets (break-in)
Engine oil and filter	Change	50 hr		First service — Drain and replace crankcase oil after first 50 hours on new generator sets
Starting Batteries	Check	50 hr		Table 5-1
Battery Electrolyte Level	Check	200 hr		Check at least every 200 hours of operation; disregard for maintenance-free battery
Anti-freeze and DCA Concentration	Check	250 hr	6 mo	Table 5-1
Coolant Filter	Change	500 hr	6 mo	Table 5-1
Cooling System	Clean	500 hr	6 mo	Table 5-1
Crankcase Breather	Clean	500 hr	6 mo	Table 5-1
Crankcase Oil and Filter	Change	250 hr	12 mo	Table 5-1 X6: if genset is used for standby applications, change oil every 12 months or 250 hours, whichever comes first
Drive Belt Tension	Check	250 hr	6 mo	Visually check belt for evidence of wear or slippage. Replace if hard or brittle. Refer to engine operation and maintenance manual.
Fuel Filter(s)	Drain	250 hr	6 mo	Table 5-1
Fuel Filters	Change	250 hr	6 mo	Table 5-1
Governor Adjustment	Check	250 hr	3 mo
Radiator Hoses for Wear & Cracks	Check	250 hr	6 mo	Table 5-1
Compressor oil	Change	1000 hr	24 mo	CPS 11-10 and CPS 11-14: 1000 hours or once in every two years
Generator bearing	Inspect	1000 hr		Inspect for wear every 1000 hours by an Onan Distributor
Valve Lash	Adjust	1000 hr		Table 5-1: after 1000 hours; contact an authorized service center for service
Alternator bearings (sealed)	Inspect	4000 hr		Inspect all sealed bearings every 4000 to 4500 hours (10000 hr/2 years)
Generator bearing	Replace	10000 hr	24 mo	Prime power: every 10,000 hours or after two years; standby power: every five years
Alternator bearings (sealed)	Replace	30000 hr		Replace all sealed bearings every 30000 hr/5 years (or if necessary after 10000 hr/2 years)
Air cleaner element	Change	500 hr	12 mo	Yearly or sooner if service indicator pops up
Generator Set Exercise	Test		1 mo	Exercise the generator set at least once a month for a minimum of 30 minutes, under not less than 30 percent of the nameplate rating

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Clearance around generator set for maintenance and service access	1	meter (3 feet)
Clearance	Exhaust pipe clearance from combustible wall or partition	12	inches (305 mm)	minimum
Clearance	Float switch lift below C-clip stop	1/8	inch (3 mm)
Clearance	Fuel line clearance from electrical wiring	1/2	inch (12.7 mm)	minimum
Clearance	Fuel line clearance from hot exhaust parts	2	inch (51 mm)	minimum
Clearance	Overspeed switch magnet-to-fly arm air gap (minimum)	0.005	inches (0.13 mm)
Clearance	Vibration isolator base elevation (max difference between isolator bases)	0.25	inch (6 mm)
Clearance	Vibration isolator top plate to base clearance	0.25	inch (6 mm)	nominal, minimum
Gap	Mechanical overspeed switch air gap between magnet and fly arm (replace switch if less)	0.005	inches (0.13 mm)
Other	AC waveform Total Harmonic Distortion (THDV)	< 5% no load to full linear load, < 3% for any single harmonic	%
Other	AVR DROOP preset at factory	five percent droop at full load and zero power factor
Other	Amperage	222.1	A	rated
Other	Automatic stop delay after normal power source returns	about 15 minutes	minutes
Other	Battery charging alternator	65	amps
Other	Battery electrolyte corrected specific gravity (fully charged)	1.260		electrolyte temperature corrected
Other	Battery electrolyte specific gravity (fully charged)	1.260	specific gravity	corrected to 80 F (27 C)
Other	Battery electrolyte specific gravity charge threshold	1.215	specific gravity	charge battery if reading is below this value
Other	Battery recharge threshold specific gravity	1.215
Other	Battery specific gravity recharge threshold	1.260	specific gravity	recharge if below
Other	Battery specific gravity temperature correction	four gravity points (0.004) for every ten degrees above 80 F (27 C)
Other	Battery specific gravity, fully charged	approximately 1.260	at 80°F (27°C)
Other	Cool-down at idle	0−30	min
Other	Coolant level below radiator cap opening	2	inches
Other	Coolant level below radiator cap opening	about two inches (50 mm)	mm	cold engine
Other	Customer output relay contacts rating (TB1 outputs 1-4)	2	amps at 30 VDC	normally open contacts
Other	Cycle crank crank and rest time	7 to 20	seconds
Other	Cycle crank number of cycles	3, 4, or 5
Other	Cycle cranking option	15	seconds	15 s crank, 15 s rest, 3 cycles
Other	Default start cycles	3	cycles	15 seconds of cranking and 15 seconds of rest
Other	ECM fuse F1 (starter solenoid circuit)	20	amps
Other	ECM fuse F2 (fuel solenoid circuit)	20	amps
Other	ECM fuse F3 (continuous B+ to remote circuits)	15	amps
Other	ECM fuse F4 (ECM circuits)	5	amps
Other	ECM fuse F5 (engine gauge circuits)	5	amps
Other	Exercise period	at least once a week for a minimum of 30 minutes with load	minutes
Other	Frequency Adjust range	5	percent of nominal frequency	e.g. 60.0 Hz adjustable 57.0 to 63.0 Hz
Other	Frequency adjustment range	±5%	%	genset running
Other	Fuse A31-F1 (control B+)	5	Amp	Engine Interface board
Other	Fuse A31-F3 (auxiliary B+)	5	Amp	Engine Interface board; panel lights, run and start relays
Other	Fuse A38-F1 (Network B+)	10	Amp	Governor Output Module
Other	Fuse A38-F2 (Switched B+)	10	Amp	Governor Output Module
Other	Fuse A38-F3 (Governor B+)	10	Amp	Governor Output Module
Other	Fuse TB-Bat F1 (Customer B+)	20	Amp	Engine Harness Assembly
Other	GOV RAMP adjustment range	0 through 10	seconds
Other	Governor droop adjustment range	within 5	percent of nominal frequency (3 Hz for 60Hz sets, 2.5 Hz for 50Hz sets)
Other	Governor regulation class	ISO8528 Part 1 Class G3
Other	Kilowatts	80	kW	rated
Other	Low oil pressure / high engine temperature fault time delay	about 10	seconds	following starter disconnect and inhibited during cranking
Other	Mounting bolts used to secure vibration isolators to base	5/8 inch or 16 mm		anchored mounting bolts
Other	Optional control relay (K11, K12, K13) contacts rating	10	amps at 600 VAC
Other	Overcrank limit (Sentinel)	60	seconds
Other	Overcrank option limit (Detector)	75	seconds
Other	Overspeed warning range 60 Hz sets	2000 to 2200	RPM
Other	Power Factor	1.0		rated
Other	Power rating reference conditions	altitude 300 feet (92 m), ambient temperature 81 F (27 C)
Other	REG VHZ adjustment range	1 through 50 (normal range 7 through 21)
Other	Rated To Idle delay	0−10	sec	Beginning Version 2.303; default = 0
Other	Response jumper setting - 90 to 550 kW	B to C
Other	Response jumper setting - over 550 kW	A to B
Other	Response jumper setting - under 90 kW	A to C

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Ambient	Capacity	Notes
Coolant		soft water/E.G./DCA mixture			Installation review checklist item: cooling system must be filled with soft water/E.G./DCA mixture.
Coolant	50/50 mix of water and antifreeze	Balanced coolant mixture of water, antifreeze and coolant additives			Drain and replace the mixture every 6 months or after 500 hours of operation. Do not add cold coolant to a hot engine; allow engine to cool below 120 F (50 C) before adding coolant.
Coolant	Water/antifreeze mixture				Permanent type antifreeze mixed per supplier for lowest expected ambient; do not use anti-leak additives
Coolant	water/antifreeze mixture			21.0 litres	Capacity with standard radiator 5.5 gallons (21 litres) for 37 DGBA, 35 DGBB, 40 DGBC, 50 DGCA, 60 DGCB; 6.5 gallons (25 litres) for 80 DGDA, 100 DGDB. Do not use antifreeze with anti-leak additives.
Engine oil		Refer to Cummins engine Operation and Maintenance Manual for lubricating oil recommendations/specifications		16.0 L	Oil capacity with filters 17 Qts (16 L); gensets are shipped with oil added
Engine oil	5W (Synthetic Oil)	API CC/CD, sulphated ash max 1.85%	below -23°C		Below -10 F (-23 C) and below; pour point 9 F (5 C) below lowest expected temperature
Engine oil	SAE 5W synthetic	API class CC/CD; sulphated ash content does not exceed 1.85 percent; pour point 9 F (5 C) below lowest expected temperature; viscosity 10,000 mPa s max at -31 F (-35 C) and 4.1 mm2/s min at 212 F (100 C)	below -23°C		For ambient temperature consistently below -10 F (-23 C) with no provision to keep engine warm; do not use petroleum base 5W grade oil
Engine oil	SAE 10W30 / SAE 15W40 / SAE 20W40 (spec table)		-25°C to 35°C	11.0 litres	Specifications table: Oil Capacity with Filters 11.5 quarts (11 litres) for 37 DGBA, 35 DGBB, 40 DGBC, 50 DGCA, 60 DGCB; 17.3 quarts (16 litres) for 80 DGDA, 100 DGDB. Oil type -13 F to 95 F (-25 C to 35 C) SAE 10W30; 14 F (-10 C) and above SAE 15W40; 32 F (0 C) and above SAE 20W40
Engine oil	10W-30	API CC/CD	-23°C to -10°C		-10 F (-23 C) to 14 F (-10 C)
Engine oil	SAE 10W-30	API Class CC/CD (max sulphated ash 1.85 percent)	-23°C to -10°C		-10 F (-23 C) to 14 F (-10 C)
Engine oil	15W-40	API CC/CD	above -10°C		14 F (-10 C) and above
Engine oil	SAE 15W-40	API Class CC/CD (max sulphated ash 1.85 percent)	above -10°C		14 F (-10 C) and above
Engine oil	20W-40	API CC/CD	above 0°C		32 F (0 C) and above
Engine oil	SAE 20W-40	API Class CC/CD (max sulphated ash 1.85 percent)	above 0°C		32 F (0 C) and above
Fuel	ASTM No. 2 Diesel	ASTM No. 2			Cummins engines on DG series sets normally use ASTM No. 2 Diesel; will operate on alternate diesel fuels within engine manual specifications. Never use galvanized or copper fuel lines, fittings or tanks.
Fuel	ASTM No. 2 diesel fuel				Cummins engines normally use ASTM No. 2 diesel fuel; will operate on alternate diesel fuels within specifications in Cummins engine Operation and Maintenance Manual.
Fuel	No. 2 diesel				No. 1 fuel or similar acceptable; consult engine manufacturer for non-standard fuel
Fuel	No. 2 diesel fuel				Engine will also operate on No. 1 fuel or other similar fuels; consult engine manufacturer for specific requirements
Fuel	Number 2 diesel fuel				Direct injection fuel system
Fuel	diesel				Do not use zinc coated or copper fuel lines with diesel fuel.
Fuel	number 2 diesel fuel				Direct injection fuel system; single element 10 micron spin-on fuel filter with water separator
Hydraulic oil	DOT-3				Trailer master cylinder reservoir - keep at least half full

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Fault codes

Code	Name	Meaning	Severity	Action
101	IDLE MODE	Indicates that the engine is operating in idle mode. Grounding the engine idle input inhibits generator build-up and governs the engine at 800 RPM; control lowers oil pressure warning and shutdown trip points accordingly.	Warning	None required; removing ground returns the genset to normal speed and voltage.
102	EMERGENCY STOP	Indicates local or remote Emergency Stop.	Shutdown	Pull the button out (turn clockwise to allow it to pop out); move Run/Off/Auto switch to Off; press the Reset switch; select Run or Auto as required. Reset only at the PCC front panel.
121	SPEED SIGNAL LOST	Mag pickup speed indication is not being sensed.	Shutdown	Restart and check RPM on digital display; inspect MPU wires/connector pins; check for 3.5 to 15 VAC at MPU while cranking.
135	OIL PRESSURE SENSOR H	Engine oil pressure sender signal is shorted high.	Warning	Check sender/connectors/wires; verify fault simulation not enabled; check 0.5 to 4.5 VDC at P7-13 (OP OUT) and P7-17 (OP COM).
141	OIL PRESSURE SENSOR L	Engine oil pressure sender signal is shorted low.	Warning	Check sender/connectors/wires; check for shorts/open circuits at P7-13, 17, 21.
143	PRE-LOW OIL PRES	Engine oil pressure dropped to an unacceptable level.	Warning	Check oil level, lines and filters; replenish if low; if powering critical loads wait until next shutdown period and follow code 415.
144	COOL SENSOR HIGH	Engine coolant temperature signal is shorted high.	Warning	Check sender/connectors/wires; check resistance between P7-30 (IH20) and P7-34 (IH20 COM).
145	COOL SENSOR LOW	Engine coolant temperature signal is shorted low.	Warning	Check sender/connectors/wires; check for shorts at P7-30 and P7-34.
146	PRE-HIGH COOL TMP	Engine has begun to overheat (coolant temperature risen to an unacceptable level).	Warning	Reduce load; check air inlets/outlets and remove obstructions to airflow; if engine can be stopped follow code 151.
151	HIGH COOLANT TEMP	Engine has overheated (coolant temperature above the shutdown trip point).	Shutdown	Allow engine to cool; check coolant level; check airflow obstructions; check fan belt; check blower fan/remote radiator pumps; reset control and restart.
197	LOW COOLANT LEVEL	Engine coolant level has fallen below the warning trip point.	Warning	Allow engine to cool; check coolant level and replenish; look for leaks; reset control and restart.
200	LOW OIL PRESSURE	Indicates engine oil pressure has dropped to an unacceptable level.	Warning	If powering critical loads and cannot be shut down, wait until next shutdown period then follow the 201-SHUTDOWN procedure. Check oil pressure via the Oil Pressure menu prior to clearing the fault.
201	LOW OIL PRESSURE	Indicates engine oil pressure has dropped below the shutdown trip point.	Shutdown	Check oil level, lines and filters; if oil system is OK but oil level is low, replenish; reset control and restart. Oil pressure limits are listed in Table 4-3.
204	OIL PRES SENDER	Indicates that the control has sensed that the engine oil pressure sender is out of its working range.	Warning	Check that the engine oil pressure sender is properly connected.
210	LOW COOLANT TEMP	Warning occurs when engine coolant temperature is 70 deg F (21 deg C) or lower while set is not operating.	Warning	Indicates engine coolant heater is not operating or is not circulating coolant; check coolant heater power supply/fuse, low coolant level, and open heater element.
211	HIGH COOLANT TEMP	Indicates engine coolant temperature is getting close to the recommended maximum (215 deg F/102 deg C standby or 207 deg F/97 deg C prime).	Warning	Reduce load if possible; check air inlets and outlets and remove obstructions to airflow; if engine can be stopped follow the 212-SHUTDOWN procedure.
212	HIGH COOLANT TEMP	Indicates engine has overheated (coolant above 223 deg F/106 deg C standby or 215 deg F/102 deg C prime).	Shutdown	Allow engine to cool; check for obstructions to cooling airflow, check fan belt, check coolant mixture, check blower fan and circulation pumps; reset control and restart after correcting problem.
213	COOLANT SENDER	Indicates that the resistance of the coolant temperature sender is out of range.	Warning	Check the resistance of the sender (should be 500 to 2k ohms).
214	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Warning	Allow engine to cool; check coolant level in radiator and recovery bottle and replenish if low; check for possible coolant leakage points.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the shutdown trip point.	Shutdown	Check coolant level in radiator and recovery bottle and replenish if low; check defective coolant bottle hose or radiator cap; reset control and restart after correcting problem. Will not occur in Idle mode.
220	MAG PICKUP	Indicates mag pickup speed indication is not being sensed or does not match generator set output frequency.	Shutdown	Restart and check RPM on the digital display; isolate per troubleshooting table 4-18.
221	FAIL TO CRANK	Indicates possible fault with control or starting system.	Shutdown	Check fuse F3 on the Engine Interface board; clean battery cable connections; recharge or replace battery.
222	OVERCRANK	Indicates possible fuel system problem.	Shutdown	Check for empty fuel tank, fuel leaks, or plugged fuel lines; check for dirty fuel filter and replace; check for dirty or plugged air filter and replace; reset control and restart.
223	OVERSPEED	Indicates engine has exceeded normal operating speed (115% +/-1% of nominal).	Shutdown	Inspect mechanical fuel linkage; check EFC for binding/damage; monitor PCC duty cycle and replace A32 or A38 as indicated.
224	FAIL TO SYNCHRONIZE	The generator set has not synchronized to the system bus within the allowable time frame.		Check governor system stability and adjust governing/synchronizer parameters; check for fuel system problems causing engine instability; widen synchronizing window and reduce acceptance time delay.
226	FAIL TO CLOSE	Indicates that the paralleling breaker has been given a signal to close, but has not closed properly.		Verify charging mechanism of paralleling breaker; check the close signal to the breaker; verify auxiliary contact signals from the breaker to the control are operational.
230	LOW DC VOLTAGE	Indicates battery voltage is below 10 VDC.	Warning	Check battery charger fuse and recharge or replace battery; clean and tighten battery cable connections; check engine DC alternator; check battery charge voltage float level.
231	HIGH DC VOLTAGE	Indicates battery voltage exceeds 32 VDC.	Warning	Check voltage float level on battery charger (lower float level); check engine DC alternator and replace if normal charging voltage is not obtained.
232	WEAK BATTERY	Indicates battery voltage drops below 60% of nominal for two seconds during starting.	Warning	Discharged or defective battery; see warning message 230, LOW DC VOLTAGE.
234	OVERSPEED	Engine has exceeded normal operating speed.	Shutdown	Clear fault and restart genset; check fault threshold; monitor RPM; check electronic governor actuator.
235	LOW COOLANT LEVEL	Engine coolant level has fallen below the shutdown trip point.	Shutdown	Check coolant level and replenish; look for leaks; reset control and restart.
240	LOW FUEL-DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.
241	LOW FUEL	Indicates fuel supply is running low.	Warning	Check fuel supply and replenish as required.
250	EEPROM ERROR	Indicates PCC memory error - data corruption of critical operating parameters.	Shutdown	Perform initial start setup; turn Run/Off/Auto to Off and reset; if the same EEPROM ERROR message occurs, replace the digital board (A32).
251	EEPROM ERROR	Indicates PCC memory error - data corruption of noncritical operating parameters.	Warning	Perform adjustment procedures and save; if the same EEPROM ERROR message occurs, replace the digital board (A32).
252	EEPROM ERROR	Indicates PCC memory error - data corruption of noncritical operating parameters.	Warning	Verify values/choices selected and repeat the save operation; if the same EEPROM ERROR message occurs, replace the digital board (A32).
260	CUSTOMER FAULT 1	Customer defined input closed to ground; message is editable.		Isolate the source of the false signal; check A34 LED corresponding to the fault input.
261	GROUND FAULT	Customer defined input closed to ground (default message); message is editable.		Isolate the source of the false signal; check A34 LED corresponding to the fault input.
262	RUPTURE BASIN (DAY TANK)	Customer defined input closed to ground; message is editable.		Isolate the source of the false signal; check A34 LED corresponding to the fault input.
263	HIGH GEN TEMP	Customer defined input closed to ground (default message); message is editable.		Isolate the source of the false signal; check A34 LED corresponding to the fault input.
270	PHASE ROTATION	The phase relationship between the generator set and the system bus is not matched.	Shutdown	Using a phase rotation checker, verify that the generator set phase rotation matches the system bus; verify control wiring to the bus PT module is properly connected.
272	FIRST START	The PowerCommand control is not receiving a proper signal from the system master first start sensor.	Warning	Control reverts to fallback mode; verify the Master First Start Sensor is functioning and that the voltage pulse is present at the PowerCommand control (terminal TB1-50); check interconnection wiring.
301	HIGH AC VOLTAGE	Indicates that one or more phase voltages has exceeded 130% of nominal, or exceeded 110% of nominal for 10 seconds.	Shutdown	Isolate the regulator module (A37), engine interface board (A31), digital board (A32), PMG/field wiring or PT/CT sensing path per troubleshooting table 4-29.
303	LOW AC VOLTAGE	Indicates that one or more phase voltages has dropped below 85% of nominal for 10 seconds.	Shutdown	Check PMG or field wiring, rotating rectifier diodes, overload, loose connectors, and voltage sensing circuitry per troubleshooting table 4-30.
313	UNDER FREQUENCY	Indicates that engine speed has dropped below 90% of nominal for 10 seconds. (Five seconds before shutdown, a Load Dump signal is initiated.)	Shutdown	Check fuel supply, intake air supply and load; check Initial Setup (set size).
320	OVERCURRENT	Indicates that generator output current has exceeded 110% of rated for 60 seconds.	Warning	Check load and load lead connections.
321	OVERCURRENT	Indicates that generator output current has exceeded 110% of rated, and a PCC time/current calculation has initiated an overcurrent shutdown.	Shutdown	Check load and load lead connections.
322	SHORT CIRCUIT	Indicates that generator output current has exceeded 175% of rated.	Shutdown	Check load and load lead connections.
330	OVERLOAD	Indicates that three-phase power output exceeds 105% of standby (or 115% of prime) rating.	Warning	Check load and load lead connections.
335	REVERSE POWER	Indicates that power is flowing into the generator set rather than out from the unit.	Shutdown	Verify connection of generator set CT's; verify proper connection of load sharing lines; verify correct frequency and voltage on all sets.
337	LOSS OF EXCITATION	Indicates that the alternator excitation system is improperly adjusted or has failed.	Shutdown	Check output voltage with calibrated meter and adjust; check load sharing lines; see Section 6 Servicing the Generator.
359	FAIL TO START	Engine cranks but fails to start (possible fuel system problem).	Shutdown	Check for empty fuel tank, fuel leaks, or plugged fuel lines; replace dirty fuel filter; replace dirty air filter; reset control and restart.
415	LOW OIL PRESSURE	Engine oil pressure has dropped below the shutdown trip point.	Shutdown	Check oil level, lines and filters; replenish if low; reset control and restart.
421	OIL TEMP	Engine has begun to overheat (oil temperature above unacceptable level) (Optional).	Warning	Reduce load; check air inlets/outlets; if engine can be stopped follow code 151 and check engine oil level.
441	LOW BAT VOLTAGE	Battery voltage supply to the control approaching a low level.	Warning	Check battery charger fuse; recharge or replace battery; clean and tighten cable connections; check engine DC alternator.
442	HIGH BAT VOLTAGE	Battery voltage supply approaching a high level at which control damage can occur.	Warning	Check float level on battery charger; check battery wiring/calibration.
1122	Rated/Idle Trans	Rated/Idle transition	Info
1123	SHUTDOWN AFTER BS	A shutdown fault occurred while Battle Short was enabled and transitioned from enabled to disabled.	Shutdown	Review Fault History and perform corrective action.
1124	DELAYED SHUTDOWN	A shutdown fault became active while the Delayed Shutdown feature was enabled.	Warning	Review Fault History and perform corrective action.
1131	BATTLE SHORT ACTIVE	Control is in Battle Short mode (bypasses several critical fault shutdowns).	Warning	None; used for genset operation during emergencies.
1311	Customer Input #1	Customer input #1 (optional customer selection)		Programmable (service tool): enable/disable input (default enable); status, warning or shutdown (default #1 = None); active closed or open (default closed [ground]); change display name up to 19 characters.
1311, 1312, 1317, 1318	CUSTOMER INPUT #1 - #4	Optional customer-selected fault input is active.		Disconnect signal lead from TB1 and reset the control; check external wiring/active input selection.
1312	Customer Input #2	Customer input #2 (optional customer selection)		Programmable (service tool): enable/disable input (default enable); status, warning or shutdown (default #2 = Warning); active closed or open (default closed [ground]); change display name.
1313−1316	Network Fault 1 thru 4	Network fault 1 through 4
1317	Customer Input #3	Customer input #3 (optional customer selection)		Programmable (service tool): enable/disable input; status, warning or shutdown; active closed or open; change display name.
1318	Customer Input #4	Customer input #4 (optional customer selection)		Programmable (service tool): enable/disable input; status, warning or shutdown; active closed or open; change display name.
1334	CRIT SCALER OR	Incorrect feature or calibration was entered into control.	Shutdown	Reload correct feature/calibration file.
1335	NONCRIT SCALER OR	Incorrect feature or calibration was entered into control.	Warning	Reload correct feature/calibration file.
1337	No Message	No message	Info
1416	FAIL TO SHUTDOWN	Genset continues to run after receiving shutdown command (Battle Short feature enabled).	Warning	Check Battle Short feature setting.
1417	POWER DOWN ERROR	Controller cannot power down because of an unknown condition.	Warning	Check for possible battery drain.
1433	EMERGENCY STOP	Local Emergency Stop.	Shutdown	Pull the button out; move switch to O; press Fault Acknowledge/Reset; select Manual or Auto.
1434	REMOTE E-STOP	Remote Emergency Stop.	Shutdown	See code 1433 to reset.
1435	LOW COOLANT TEMP	Engine coolant heater is not operating or not circulating coolant (coolant <=70 F [21 C]).	Warning	Check coolant heater power/fuse/cord; check coolant level; check heater element (10 to 60 ohms); check sensor.
1438	FAIL TO CRANK	Engine failed to crank after the PCC received a start signal.	Shutdown	Test for B+ at the starter; check fuse F3 (2 Amps); check K4 start pilot relay and starter circuitry; refer to code 121.
1442	WEAK BATTERY	During cranking battery voltage at or below weak battery trip point.	Warning	Recharge or replace battery; check electrolyte level and connections; check harness.
1443	BATTERY FAILED	Dead battery - engine will not start.	Shutdown	See code 1438 instructions.
1444	KW OVERLOAD	Generator output power exceeded 105% of genset rating (3 sec at 110% of rated).	Warning	Check load and load lead connections; check CTs and CT connections.
1445	SHORT CIRCUIT	Generator output current exceeded 175% of rated.	Shutdown	Check load and load lead connections (fault may not reset for several minutes).
1446	HIGH AC VOLTAGE	Phase voltage exceeded 130% of nominal, or 110% of nominal for 10 seconds.	Shutdown	Check fault simulation; clear fault and restart; refer to Generator/Base Board Isolation Procedure.

Showing the first 80 of 145 codes.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Adjusting Default Settings (Controller Configuration Menu) adjustment

Make sure Main Menu 1 is displayed and simultaneously press the Home Menu and Previous Main Menu buttons.
Press the buttons next to the and symbols to navigate between the three submenus.
Press the button next to the symbol until the + and − symbols are displayed.
Press the button next to the + or − symbol to select the desired option.
Press the symbol to save the changes.

Adjusting Values/Parameters (Adjust Menu) adjustment

⚠ If the Home button or Previous Main Menu button is pressed before pressing the save symbol, the changes are not saved.

⚠ Long periods of engine idling can eventually affect engine performance and may void engine warranty.

Press the button next to the symbol in the display until the + and − symbols are displayed.
If necessary, press the button next to the or symbols to move to the numeric character you wish to change.
Press the button next to the + symbol to increase the value; press the button next to the − symbol to decrease the value.
After adjusting, press the symbol to save; make sure the cursor is on the last numeric character before pressing.

Adjusting Values/Parameters (PowerCommand 2100 Control) adjustment

Press the button next to the down arrow symbol until the + and - symbols are displayed.
Press the button next to the arrow symbols to move to the numeric character to be changed.
Press the button next to + to increase the value or select a parameter; press - to decrease.
Press the save symbol to save the changes (make sure the cursor is on the last numeric character).
If the Home button or Previous Main Menu button is pressed before the save symbol, the changes are not saved.

Controller Configuration (PowerCommand 2100 Control) adjustment

Make sure Main Menu 1 is displayed.
Simultaneously press the Home Menu and Previous Main Menu buttons to view the first Controller Configuration menu.
Press the buttons next to the up and down symbols to navigate between menus.
Press the button next to the + or - symbol to select the desired option.
Press the save symbol to save changes; pressing Home or Previous Main Menu before the save symbol leaves changes unsaved.

Convert Day Tank Controller 240 VAC to 120 VAC adjustment

Remove the two jumpers between terminals TB1-6 and TB1-7.
Connect one jumper between TB1-5 and TB1-6 and the other between TB1-7 and TB1-8.
Move selector switch S103 on the control PCB to the up position for 120V.
If equipped with a transformer, remove jumpers between H2 and H3 and connect one between H1 and H3 and the other between H2 and H4.

Day Tank Controller Conversion 240 VAC to 120 VAC adjustment

Remove the two jumpers between terminals TB1-6 and TB1-7 and connect one between TB1-5 and TB1-6 and the other between TB1-7 and TB1-8.
Move selector switch S103 on the control PCB to the up position for 120V.
On the control transformer, remove the two jumpers between terminals H2 and H3 and connect one between H1 and H3 and the other between H2 and H4.

Dip Adjustment adjustment

Turn the DIP pot clockwise to increase the voltage vs frequency slope for frequencies below the UFRO threshold.
Greater slope gives greater voltage roll off as frequency drops, easing large load pickup but increasing voltage dip.
Turn the pot fully counterclockwise to make the slope the same above and below the threshold frequency.

Dwell Adjustment adjustment

Turn the DWELL pot clockwise to increase dwell time (voltage recovery time when frequency dips below threshold).
Turn the DWELL pot fully counterclockwise to eliminate dwell.
With no dwell, voltage recovery follows engine speed recovery.

Electric Governor Controller Adjustments adjustment

⚠ If adjustment must be made while the unit is running, use extreme caution around hot manifolds and moving parts

Tools: Frequency meter

Move RUN/STOP/REMOTE switch to RUN and operate set at no load.
Confirm DROOP potentiometer adjust is set at zero position.
Set speed by adjusting the SPEED potentiometer to 50 or 60 Hz.
Adjust GAIN potentiometer clockwise until engine starts to hunt, then counterclockwise until speed is stable.
Adjust the 'B' potentiometer the same as GAIN.
Adjust the 'I' potentiometer to decrease overshoot above rated speed.
Apply 1/4 load and adjust the GAIN potentiometer again.
Apply full load to be certain the set will carry it; lengthen actuator linkage if it will not.

Governor Adjustments (Type A Electric Governor) adjustment

Set selector switch S1 to OFF, S2 to appropriate model position.
Set pots initially: Gain 20%, I 20%, D 30%, Droop 0%.
Start set, adjust Speed pot for required frequency (60Hz=1800RPM or 50Hz=1500RPM) at operating temperature.
Disconnect load, turn Gain pot to 100% or until unstable, then back off until stable.
Adjust D and I pots similarly; readjust Speed if necessary.
Push throttle to minimum speed, release and observe overshoot (2-5 Hz acceptable); adjust I pot to reduce overshoot or hunting.

Initial Start Setup adjustment

⚠ Selecting this menu resets all operating parameters to default values; perform only by technically qualified personnel.

Press RESET, MENU and PHASE SELECT simultaneously to invoke the Initial Start Setup menu.
Toggle the Standby/Prime option.
Select the correct generator set model, frequency and kW rating.
Select the correct nominal line-to-line output voltage.
Select DELTA or WYE.
Select SAVE to save changes; MAIN MENU is then displayed.

Mechanical Governor Adjustment adjustment

Tools: Accurate frequency meter

Using an accurate frequency meter, measure frequency under full load.
Turn the speed adjustment screw on the governor to adjust to nominal 50 or 60 Hz.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

Voltage	Phase	Connection	Leads	Notes
		AVR response jumper	A to C	For generator output 90 kW or less (SX440 and MX321)
		Auxiliary terminal board TB21	K1, K2, P2, P3, P4, S2, S1, A2, A1	A1 and A2 connect a VAR/power factor controller when paralleling with a utility; S1 and S2 connect a droop compensating CT when paralleling with a generator set or utility
		CT1 - U load leads (A phase); CT2 - V load leads (B phase); CT3 - W load leads (C phase)	6 lead gensets: generator output leads routed through CTs; 12 lead gensets: load wires routed through CTs	12-lead sets have dual secondary CTs (3 pins); 6-lead sets have single secondary CTs (2 pins)
		Day tank LO SHUTDOWN engine shutdown connection	TB1-14 to engine block ground; TB1-15 to TB2-16 on the ECM
		Fault relay K8/K9 (Dry Contact Module)	K8=Over Crank, Low Oil Pressure, High Engine Temperature, Low Coolant Level, Low Fuel Level; K9=Low Fuel Level, Rupture Basin	Contact ratings: 40A max carry/break N.O. 12V coil, 30A N.C. 12V coil, 20A N.O./10A N.C. 24V coil
		MX321 PMG-excited jumper positions	2-3, 4-5 and 6-7	These jumpers must be in these positions
		MX321 voltage regulator frequency jumper	3-2 for 50 Hz; 3-1 for 60 Hz
		SX440 voltage regulator frequency jumper	C-50 for 50 Hz; C-60 for 60 Hz
		TB3 (ECM alternative RUN/STOP/REMOTE connection)	TB3-1=REMOTE, TB3-2=RUN, TB3-3=STOP	Provides alternative direct connection to ECM for troubleshooting or customer connection
		Voltage trimmer R21	voltage regulator terminals 1 and 2	There must be a jumper between terminals 1 and 2 when voltage trimmer R21 is not used
	single phase	QSG-Series power distribution panel voltage selector switch S1 position	main output terminals	Rotary switch under lockable cover selects 120/240 VAC single phase
	single phase	Voltage regulator terminal 6	jumpered to terminal 8	When the generator is connected for single-phase output, terminal 6 is not connected to the isolation transformer
	three phase	QSG-Series power distribution panel voltage selector switch S1 position	main output terminals	Rotary switch selects 120/208 VAC three phase
110V - 120V L-N	Single phase, 2-wire	Jumper locations for single phase, 2-wire		PTC Module AC wiring (0300-5382-01, -02)
120	single phase	Day tank fuel pump control power reconnection	move jumpers from TB1-6/TB1-7 to TB1-5/TB1-6 and TB1-7/TB1-8	Move selector switch S103 on the control PCB to the up position for 120 V (factory set for 240 V, S103 down)
190, 200, 208, 220, 230, 240, 380, 416, 440, 460, 600 (L-L)	3 (three phase)	3 or 4 wires		Voltage Configuration submenu; default = 3Ph 208V 4W
190V - 240V L-L	Three phase	Jumper locations for three phase, 190V-240V L-L		Use 0300-5382-01 for 190V-240V L-L, 50/60 Hz
200, 220, 230, 240 (L-L)	1 (single phase)	3 wires		Voltage Configuration submenu (Governor/Regulator Setup)
200V - 240V L-L	Single phase, 3-wire	Jumper locations for single phase, 3-wire		PTC Module AC wiring
24		Day tank fuel pump control logic power (two lead harness, no transformer)	TB1-19 to positive (+) 24 V starter motor solenoid; TB-20 to negative (-)	Provides 24 VDC for the control circuit
240	single phase	Day tank fuel pump control default factory connection	jumpers between terminals TB1-6 and TB1-7	Selector switch S103 on the control PCB in the down position for 240 V
380V - 600V L-L	Three phase	Jumper locations for three phase, 380V-600V L-L		Use 0300-5382-02 for 380V-600V L-L, 50/60 Hz

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Parts cataloged across the Cummins/Onan 6BT5.9 family

Part #	Description	Category
982-0200	Air Filter	Air filter
FP-3034946	Multi-Groove Fan Belts (Ribbed 8) (62.5" X 1.125")	Belt
FP-3911558	Belt, V Ribbed (Alternator)	Belt
3824469	fuel pump gear puller	Fuel pump
DM-3801372	Gasket Set - 6BT 5.9	Gasket
FP-3901356	Turbo Charger Mounting Gasket	Gasket
FP-3926760	Gasket, Oil Cooler Core	Gasket
FP-3928493	Gasket, Rear Cover	Gasket
FP-3929792	Gasket, Filter Head	Gasket
FP-3937706	Turbocharger Oil Drain Gasket (H x 35)	Gasket
FP-3938157	Gasket, Pick-Up Tube	Gasket
FP-3938158	Gasket, Air Intake Connection	Gasket
FP-3939258	Gasket, Fuel Transfer Pump Mounting	Gasket
FP-3959052	Gasket, Oil Pan	Gasket
FP-6B59PREM	6B/6BT5.9 In-Frame Kit w/upper gasket set & oil pan gasket	Gasket
FP-6B59PREML	6B/6BT5.9 In-Frame Kit w/upper gasket set & oil pan gasket (late)	Gasket
FP-IFK6B59PREM	6B/6BT5.9 In-Frame Kit w/upper gasket set & oil pan gasket	Gasket
FP-IFK6B59PREML	6B/6BT5.9 In-Frame Kit w/upper gasket set & oil pan gasket (late)	Gasket
3822509	Injection Pump Bore Brush Service Tool	Injector
3823276	injector bore brush	Injector
DM-3029551	Fuel Injector - 6BT 5.9	Injector
LF3349	Lube, Full-Flow Spin-On	Oil filter
3377259	bosch timing tool (ve)	Service part / kit
965-0520	Cooling Fan	Service part / kit
DM-3802010	Main Bearing Set Standard - 4BT 3.9, 6BT 5.9, 6CT 8.3	Service part / kit
FP-3356970	6B/6BT5.9 In-Frame Kit (contains FP-3802160 Piston Kit)	Service part / kit
FP-3356971	6B/6BT5.9 In-Frame Kit (contains FP-3802248 Piston Kit)	Service part / kit
FP-3903575	Kit, Solenoid 12 Volt	Service part / kit
FP-3903576	Kit, Solenoid 24 Volt	Service part / kit
FP-3910739	Bearing, Ball (Fan Drive)	Service part / kit
FP-3918428	Plunger, Pressure Regulator	Service part / kit
FP-3957544	Element, Oil Cooler	Service part / kit
GM12641	Safety/locking agent	Service part / kit
GM12657	Dipstick	Service part / kit
GM12676	Cylinder liner	Service part / kit
GM12678	Screw plug	Service part / kit
GM12697	Torx-head bolt	Service part / kit
GM12921	Hexagon bolt	Service part / kit
GM12924	Rear end cover	Service part / kit
GM12936	Wrapped bearing bush	Service part / kit
GM12937	Wrapped bearing bush	Service part / kit
GM12954	Dipstick	Service part / kit
GM12970	Compression spring	Service part / kit
GM13175	Pipe clamp	Service part / kit
TB1-6	Control box terminal (TB1-6)	Service part / kit
TB1-7	B+ OUTPUT	Service part / kit
DM-3805401	Oil Pump - 6BT 5.9	Pump
DM-3805403	Water Pump - 4BT 3.9, 6BT 5.9	Pump
FP-3286277	Water Pump	Pump
FP-3928143	Pump, Fuel Transfer	Pump
FP-3970880	Pump, Fuel Transfer	Pump
FP-4939587	Pump, Lubricating Oil	Pump
FP-4947710	Pump, Fuel Transfer	Pump
509-0266-02	Ring, O	Seal
FP-3883284	Seal, O-Ring, Air Intake Connection	Seal
FP-3900808	Seal, Injector	Seal
FP-3903380	Seal, Banjo Connector (Fuel Manifold)	Seal
FP-3906659	Seal, Injector	Seal
FP-3906698	Seal, Rectangular Ring	Seal
FP-3909356	Seal, Injector	Seal
FP-3909397	Seal, O-Ring	Seal
FP-3909410	Seal, Rear Service Kit (Dry Clutch Housing)	Seal
FP-3913994	Seal, O-Ring	Seal
FP-3921640	Seal, Valve Stem (Intake & Exhaust) (For Engines Built Before April 2003)	Seal
FP-3931824	Seal, O-Ring, Turbo Oil Line	Seal
FP-3937111	Seal, Front Service Kit	Seal
FP-3957912	Seal, Valve Stem (For Engines Built After April 2003)	Seal
GM12667	Sealing ring	Seal
S103	Selector switch	Switch
DM-3015282	Thermostat 180F - 4BT 3.9, 6BT 5.9	Thermostat
FP-3802273	Kit, Thermostat (83° C), (181° F)	Thermostat
FP-3917324	Assembly, Thermostat (83° C), (181° F)	Thermostat

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Common questions

What is the oil capacity of the Cummins/Onan 6BT-5.9-G2?

The Cummins/Onan 6BT-5.9-G2 engine has an oil capacity of 16.0 liters.

What is the displacement of the Cummins/Onan 6BT-5.9-G2?

The Cummins/Onan 6BT-5.9-G2 has a displacement of 5.9 liters with 6 cylinders.

Which generators use the Cummins/Onan 6BT-5.9-G2 engine?

The Cummins/Onan 6BT-5.9-G2 powers 8 generator set(s), including AKSA ACD 125, Cummins/Onan 100 DGDB, Cummins/Onan 65DGDA, Cummins/Onan 80 DGDA, Cummins/Onan 95 DGDB.

What is a common problem with the Cummins/Onan 6BT-5.9-G2 engine?

A commonly reported issue on generators using the Cummins/Onan 6BT-5.9-G2 is: The FAULT 1 or FAULT 2 fault lamp lights. Engine shuts down immediately, engine runs for several seconds and then shuts down, or engine continues to run. Cause: The standard undesignated fault functions are programmed to shut down the set when a fault is sensed. Fault 1 is time delayed while Fault 2 is immediate. The nature of the fault is an optional selection that is determined when the set installation is designed. The undesignated fault functions may also be programmed for non-shutdown or non-time delay.