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Cummins/Onan QSX15-G9 Engine

The Cummins/Onan QSX15-G9 is a 15 L 6-cylinder turbocharged with air-to-air charge air-cooling engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, Katolight and MQ Power, including the 350DFEG, 450 DFEJ, 500 DFEK and C450D6. It holds 83.3 L (22.0 gal) of oil and 57.9 L (15.3 gal) of coolant.

Also known as: Cummins QSX15-G9, QSX15 G-9

Part of the Cummins/Onan QSX15 engine family — 19 variants share parts & fitment.

15.0 L

Displacement

Cylinders

1800 rpm

Rated speed

83.3 L

Oil capacity

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

Engine specifications

Oil capacity	83.3 L
Coolant capacity	57.9 L
Displacement	15.0 L
Cylinders	6
Aspiration	Turbocharged with air-to-air charge air-cooling
Rated speed	1800 rpm

Generator sets powered by this engine

Shared across brands: Cummins/Onan, Katolight, MQ Power

Cummins/Onan 350DFEG Cummins/Onan 450 DFEJ Cummins/Onan 500 DFEK Cummins/Onan C450D6 Cummins/Onan DFE Cummins/Onan DFEJ Cummins/Onan DFEKCummins/Onan DFEK-5737120Cummins/Onan QSX15 Katolight D500FJZ4 Katolight D500FNZ4 Katolight D500FPZ4 Katolight D500FRZ4 MQ Power CG500C2

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

Common problems

Over Current 1471
Engine Does Not Crank in Manual Mode (No Fault Message)
Cause: No power is supplied to the control. (Control Alive indicator on the base board is not flashing).
Fix: Poor battery cable connections. Clean the battery cable terminals and tighten all connections using an insulated wrench; Remove F4 and check continuity. If open, replace the fuse with one of the same type and amp rating (5 Amps); If F4 is OK, remove connector P7 and check for B+ at P7-1 through P7-4 and GND at P7-5 through P7-8; If B+ or ground missing, isolate to the harness and the TB BAT terminal mounted on the engine block; If B+ and ground check OK, the base board may be defective. Cycle power to the base board by reconnecting P7.
Low oil pressure 143
Low AC Voltage 1447
High AC Voltage 1446
Fueling actuator #2 396
Fueling actuator #1 378
Under Frequency 1448
Short Circuit 1445
Overcurrent 1472
No DC Output (No Fault Message)
Cause: Tripped DC circuit breaker
Fix: Correct the possible overload and reset the circuit breaker
Fuel temperature sensor 261
Fuel rail pressure sensor 451
EEPROM ERROR 250
Cause: Indicates PCC memory error. Data corruption of critical operating parameters.
Fix: Contact an authorized service center.
Overspeed 234

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan QSX15-G9.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter			L028-2	50 hr	eBay
Fuel filter	New o-ring seal supplied with the new filter. For Biodiesel applications use gasket pack 3950445 S (green) and change with every filter change.		—
Oil filter	Single spin-on combination full flow and bypass filters		—	500 hr
Battery	1400 Amps minimum at ambient temperature 0 °C (32 °F)		—	100 hr
Coolant	57.9 L (15.3 US gal)	57.9 L	—	8 hr
Oil	83.3 L (88.0 qt)	88.0 L	—	8 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Repair guides

Step-by-step procedures compiled from the Cummins/Onan service manual for this engine.

Service intervals

Item	Action	Hours	Months	Notes
Air cleaner	Check	250 hr	6 mo	X1; replace as necessary; refer to QSX15 engine manual
All hardware (fittings, clamps, fasteners)	Check	8 hr		Daily or after 8 hrs.
All hardware (fittings, clamps, fasteners, etc.)	Check	100 hr		Daily or after 8 hours
Anti-freeze and DCA concentration	Check	250 hr	6 mo	X1; refer to QSX15 engine manual
Coolant heater(s)	Check	100 hr		Daily or after 8 hrs.
Drive belt	Check	250 hr	6 mo	X1; refer to Cummins QSX15 Series Engine Operation and Maintenance Manual for interval/procedure
Engine oil level	Check	8 hr		Daily or after 8 hrs.
Fuel filter(s)	Drain	250 hr	6 mo	X1; refer to QSX15 engine manual
Genset	Inspect	8 hr		Daily; check for oil, fuel, cooling and exhaust system leaks
Radiator hoses for wear and cracks	Check	250 hr		Daily or after 8 hours
Charge Air Piping	Check	50 hr		Weekly
Coolant heater	Check	50 hr		Weekly or after 50 hours
Coolant level	Check	50 hr		Weekly or after 50 hours
Exhaust condensate trap	Drain	100 hr		Drain water to prevent it flowing back into the engine
Fuel level	Check	50 hr		Weekly or after 50 hours
Oil level	Check	50 hr		Weekly or after 50 hours
Air cleaner	Clean	100 hr		Monthly or after 100 hours; clean if required, perform more often in dusty conditions
Battery charging system	Check	100 hr		Monthly or after 100 hours
Battery electrolyte level	Check	200 hr	1 mo	Monthly or after 100 hrs. Also check at least every month or 100 hours of operation, whichever occurs first.
Fuel tank water and sediment	Drain	100 hr		Monthly or after 100 hours
General set inspection	Inspect	100 hr		Monthly or after 100 hours (Table 5-1, footnote X2): check for oil, fuel, cooling and exhaust system leaks; check exhaust system audibly and visually with set running
General set inspection (oil, fuel, coolant, exhaust leaks; exhaust audibly and visually with set running)	Inspect	100 hr		Monthly or after 100 hrs, whichever is sooner.
Generator air outlet	Check	100 hr		Monthly or after 100 hrs.
Radiator hoses	Check	500 hr	12 mo	Monthly or after 100 hrs; check for wear and cracks.
Starting batteries	Check	100 hr		Check condition and terminals
Oil and filter change (Generator Drive, 1500 rpm, 45 liter sump)	Change	125 hr	12 mo	fixed hour method, standby applications
Air cleaner	Replace	250 hr		Check air cleaner; replace as necessary. Refer to QSX15 manual.
Crankcase oil and filter	Change	250 hr	12 mo	Prime power: every 6 months or 250 hours; standby: every 12 months or 250 hours, whichever comes first
Drive belt tension	Check	250 hr	6 mo	Visually check belt for wear or slippage; replace if hard or brittle
Engine oil and filter	Replace	250 hr	6 mo	X1; 6 Months or After 250 Hrs; refer to QSX15 engine manual
Lubricating Oil and Filters	Change	250 hr	6 mo
Oil and filter change (Generator Drive, 1800 rpm, 95 liter sump)	Change	250 hr	12 mo	fixed hour method, standby applications
Radiator Hoses	Inspect	250 hr	6 mo	Check for wear & cracks
Supplemental Coolant Additive (SCA) and Antifreeze Concentration	Check	250 hr	6 mo
Water coolant filter	Replace	250 hr	6 mo	X1; 6 Months or After 250 Hrs
Air cleaner element	Change	500 hr	12 mo	Yearly or after 500 hours; clean if required more often
Coolant filter	Change	500 hr	12 mo	Yearly or after 500 hours; refer to engine operation and maintenance manual
Cooling system	Clean	500 hr	12 mo	Yearly or after 500 hours; drain and replace coolant mixture
Crankcase breather	Clean	500 hr	12 mo	Yearly or after 500 hours
Engine oil and filter	Change	500 hr	12 mo	Table 5-1, footnote X1

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	Angular alignment T.I.R. limit	not more than .001	in per inch of radius	center of shaft to indicator axis
Clearance	Angular alignment maximum T.I.R.	0.001	inch per inch of radius (center of shaft to indicator axis)	measuring deflection to bolt heads
Clearance	Exhaust pipe clearance from combustible wall or partition	12	inches (305 mm)	minimum
Clearance	Exhaust pipe clearance to combustible wall or partition	305	mm
Clearance	Exhaust pipe clearance to combustible wall/partition	12	inches (305 mm)
Clearance	Exhaust pipes to combustible wall or partition	305 mm (12 inches)	mm
Clearance	Float switch assembly float lift clearance below C-clip stop	1/8	inch (3 mm)	use a feeler gauge
Clearance	Fuel line clearance from electrical wiring	1/2	inch (12.7 mm)
Clearance	Fuel line clearance from hot exhaust parts	2	inch (51 mm)
Clearance	Fuel lines - minimum clearance from electrical wiring	12.7	mm
Clearance	Fuel lines - minimum clearance from hot exhaust parts	51	mm
Clearance	Fuel lines to electrical wiring	12.7 mm (1/2 inch) minimum	mm
Clearance	Fuel lines to hot exhaust parts	51 mm (2 inches) minimum	mm
Clearance	Generator mount pre-load steel spacer thickness	1 3/4	inch	two spacers under both stator foot brackets
Clearance	Generator-to-engine angular alignment (T.I.R.)	.001 in. per inch of radius (center of shaft to indicator axis), maximum	in	750 kW gensets and larger
Clearance	MPU installation gap adjustment	back out 1/4 turn after touching gear tooth	turn
Clearance	Minimum clearance of fuel lines from electrical wiring	12.7	mm (1/2 inch)
Clearance	Minimum clearance of fuel lines from hot exhaust parts	51	mm (2 inch)
Clearance	Service/maintenance access clearance around generator set	1	meter
Clearance	Vibration isolator base elevation difference	0.25	inch (6 mm)	shimmed or grouted within this of each other
Clearance	Vibration isolator clearance	0.25	inch (6 mm)
Clearance	Vibration isolator clearance between top plate and base	6 mm (0.25 inches) or greater	mm	nominal
Clearance	Vibration isolator nominal clearance (leveling bolt)	0.25	inch (6 mm)	minimum, or greater
Gap	Coolant level below radiator cap lower sealing surface	3/4 inch (18 mm)	inch (mm)
Gap	MPU sensor to flywheel ring gear tooth	back it out one quarter turn	turn	sensor threaded in until it just touches gear tooth
Other	AC control wire strip length	6.0 mm (0.236 in) screw type; 10 mm (0.75 in) push type	mm
Other	AVR Droop setting	5	% at full load, 0 PF
Other	AVR voltage regulation (load regulation)	approximately ±0.5	% RMS
Other	Air starting motor minimum air pressure	480	kPa [70 PSI]
Other	Ambient temperature below which coolant heaters recommended (NFPA 110)	40	°F
Other	Amperage PH1	0, 615, 615, 614, 613, 613, 0	A	warm up / start / 15 min / 30 min / 45 min / 1 hour / cool down
Other	Amperage PH2	0, 618, 618, 617, 618, 617, 0	A	warm up / start / 15 min / 30 min / 45 min / 1 hour / cool down
Other	Amperage PH3	0, 612, 612, 611, 611, 611, 0	A	warm up / start / 15 min / 30 min / 45 min / 1 hour / cool down
Other	Angular alignment maximum T.I.R.	.001 inches per inch of radius	in/in	center of shaft to indicator axis
Other	Battery CCA (minimum)	1400	CCA	Cold Soak @ 0° F (-18° C)
Other	Battery charging alternator output	35	Amps
Other	Battery electrolyte maximum permissible temperature during charge	45 °C (113 °F)	°C	during charge
Other	Battery electrolyte specific gravity	1.260	SG	corrected at 25 °C (77 °F); charge if below 1.215
Other	Battery electrolyte specific gravity, for filling new cells, ambient normally below 32 °C (90 °F)	1.270	SG
Other	Battery specific gravity (fully charged)	1.26	specific gravity	at 80 F (27 C)
Other	Battery specific gravity (high ambient, above 95F/35C)	1.225		recommended to reduce electrolyte loss
Other	Battery specific gravity (recharge threshold)	below 1.260
Other	Battery specific gravity charge threshold	1.215	corrected	charge battery if reading below
Other	Battery specific gravity fully charged	1.260	corrected	add 0.004 per 10 F above 80 F (27 C)
Other	Battery specific gravity state of charge 100%	1.26 to 1.28	specific gravity at 27°C [80°F]
Other	Battery specific gravity, fully charged	approximately 1.260	specific gravity	at 80 F (27 C)
Other	Battery specific gravity, fully charged, corrected	1.260	SG	at 25 °C (77 °F)
Other	Battery temperature sensor fault trip temperature (fault code 2263)	55	°C	131 °F
Other	Battery terminal cleaning solution	1/4 pound baking soda to 1 quart water
Other	CAN datalink main trunk maximum length	40	meters	no more than 30 devices
Other	CAN datalink stub maximum length	1	meter	stub from main trunk to each module
Other	CAN datalink transmission speed	250	KBaud
Other	Charge battery if specific gravity below	1.215	specific gravity
Other	Charge battery if specific gravity reading is below	1.215	SG
Other	Compression ratio	17.0:1
Other	Cooling system make-up water maximum calcium/magnesium (hardness)	170	ppm (as CaCO3)
Other	Cooling system make-up water maximum chloride	40	ppm (as Cl)
Other	Cooling system make-up water maximum sulfate	100	ppm (as SO4)
Other	Default starting cycles	3 (15 seconds cranking, 30 seconds rest)	cycles	configurable 1-7 cycles
Other	Drive belt tension new belt	1110	N [250 lbf]	10 rib

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		Refer to Cummins QSX15 Series Engines Operation and Maintenance Manual for coolant recommendations/specifications		58.0 L	Cooling System (Capacity Std. Radiator) printed as 15.3 Gal (58 L); check anti-freeze and DCA concentration
Coolant	50% ethylene glycol and water (also propylene glycol permitted)	Cummins Engineering Standard 14603; Fleetguard Compleat ES low-silicate antifreeze or equivalent; DCA4 required if not using Fleetguard Compleat		57.9 L	Coolant capacity with standard set-mounted radiator 15.3 Gal (57.9 L). Add coolant at 50 °C (122 °F) or lower. Fill to bottom of fill neck in radiator or expansion tank. Some radiators have two fill necks, both must be filled.
Coolant	Balanced coolant mixture of water and antifreeze	Refer to Cummins engine Operation and Maintenance Manual		90.0 L	Capacity with standard radiator 24 Gal (90 L); drain and replace mixture every year or after 500 hours; add until 3/4 inch (18 mm) below radiator cap lower sealing surface
Coolant	Fully formulated antifreeze/coolant	TMC RP329 (ethylene glycol) or TMC RP330 (propylene glycol)		24.0 L	50/50 mixture with quality water; engine only coolant capacity 24 liters [25 qt]. Drain and flush after 6000 hours or 3 years.
Coolant	soft water / E.G. / DCA mixture				Cooling system to be filled with soft water/E.G./DCA mixture (on-site review checklist).
Coolant	50/50 ethylene glycol antifreeze and water (0 to -32C); 60/40 ethylene glycol/water (-32 to -54C)	TMC RP329 (ethylene glycol) or RP330 (propylene glycol)	54°C to 0°C		50/50 mixture gives -36C [-34F] freezing point and 110C [228F] boiling point; do not use low-silicate antifreeze meeting ASTM D4985 for extended service intervals
Engine oil		Refer to Cummins QSX15 Series Engines Operation and Maintenance Manual for lubricating oil classification/viscosity		58.0 L	Oil Cap. w/Filters printed as 26 Gallons (58 L); gense is shipped filled with correct type and quantity of oil
Engine oil	15W-40	CES 20,076 (or CES 20071; API CH-4 alternative)			Synthetic engine oils API category III recommended for ambient temperatures consistently below -25°C [-13°F]; 0W-30 oils where ambient never exceeds 0°C [32°F]; arctic operation use synthetic CF-4/SG or CG-4/SH 5W-30 below -23°C [-10°F].
Engine oil	15W-40 (recommended); 10W-30 or 5W-30 for temperate/cold; synthetic 0W-30 API category III below -25C	CES 20071 or CES 20076 (or API CH-4); API CG-4 at reduced drain interval			Do not use API CC/CD/CE/CF (obsoleted)
Engine oil	high-quality multi-viscosity lubricating oil	Cummins Premium Blue or equivalent		83.3 L	Oil capacity with filters 88 qt (83.3 L). Do not operate with oil below the L mark or above the H mark. Special running-in oils are not recommended.
Fuel	ASTM D975 Grade 2	BS EN 590:2000 (automotive diesel); BS 2869:2010+A1:2011 (fuel oils for agricultural, domestic and industrial engines and boilers)			Never use galvanized or copper fuel lines, fittings, or fuel tanks
Fuel	ASTM D975 No. 2-D	Cetane number 40-50, 300-500 ppm Sulfur			Diesel fuel specifications
Fuel	ASTM No. 2 D diesel fuel; blends of No. 2 D and No. 1 D below 0°C [32°F]				Viscosity must be kept above 1.3 cSt at 100°C [212°F] to provide adequate fuel system lubrication.
Fuel	ASTM No. 2 diesel				Cummins engines normally use ASTM No. 2 diesel fuel.
Fuel	ASTM No. 2D diesel	BS 2869:2010+A1:2011 acceptable alternative			Minimum Cetane number 40. Cetane above 40 may be needed at high altitude or extremely low ambient temperatures. Do not mix gasoline or alcohol with diesel fuel. Keep tanks as full as possible to avoid condensation.
Fuel	Diesel				Day tank fuel transfer pump maintains reservoir of diesel fuel in the day tank.
Fuel	Diesel fuel specified to ASTM No. 2 or BS EN 590:2000, Automotive fuels	ASTM No. 2 / BS EN 590:2000			An electric solenoid valve in the supply line is recommended for all installations and required for indoor automatic or remote starting installations. Never use galvanized or copper fuel lines, fittings or fuel tanks.
Fuel	diesel	ASTM No. 2 or BS EN 590:2000			Cummins engines normally use a diesel fuel specified to ASTM No. 2 or BS EN 590:2000; alternate diesel fuels within the specifications shown in the Generator Set Operator Manual (0908-0219)
Grease	Lithium based grease	Mobilux No. 2 or Shell Alvania R3		2.74 oz (81 ml)	Generator end bearing. Temperature range -22F to +248F (-30C to +120C). Grease should be equally divided between the bearing, bearing cap cavity, and bearing cartridge cavity.
Grease	Lithium based grease, Mobilux No. 2 or Shell Alvania R3		-30°C to 120°C	2.74 oz (81 ml)	End bearing lubricant; grease equally divided between bearing, bearing cap cavity and bearing cartridge cavity.
Other	DEF (diesel exhaust fluid), if equipped				Pre-start check: DEF tank filled to normal full level; auxiliary DEF system properly connected if equipped.
Other	Donaldsons D1400 solvent				Soak air cleaner filter element at least 15 minutes in water and D1400 solvent to remove soot, carbon and dirt

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
27	Low AC voltage shutdown	Voltage on any phase has dropped below a preset value; adjustable 50-95% of reference, delay 2-20 seconds; default 85% for 10 seconds	Shutdown	Genset shut down on low AC output voltage
32	Reverse power shutdown	Adjustment range 5-20% of standby kW rating, delay 1-15 seconds; default 10%, 3 seconds	Shutdown	Genset shut down on reverse power
59	High AC voltage shutdown	Output voltage on any phase exceeds preset values; adjustable 105-125% of nominal, time delay 0.1-10 seconds; default 110% for 10 seconds	Shutdown	Genset shut down on high AC output voltage
81 o	Over frequency shutdown/warning	Generator set is operating at a potentially damaging frequency level; 2-10 Hz above nominal, 1-20 second delay; default 6 Hz, 20 seconds, disabled	Shutdown	Shutdown/warning on over frequency
81 u	Under frequency shutdown	Generator set output frequency cannot be maintained; 2-10 Hz below reference, 5-20 second delay; default 6 Hz, 10 seconds	Shutdown	Genset shut down on under frequency
101	IDLE MODE	Indicates that the engine is operating in idle mode (governed at 800 RPM, generator build-up inhibited).	Warning	Remove ground from engine idle input to return to normal speed and voltage.
102	EMERGENCY STOP	Indicates local or remote Emergency Stop.	Shutdown	Turn the switch clockwise and allow it to pop out (local only). Move the Run/Off/Auto switch to Off. Press the Reset switch. Select Run or Auto, as required.
111	Internal ECM error	Category A	Shutdown
112	Actuator not responding	Category A	Shutdown
113	Actuator sensor fault	Category B	Warning
115	No speed signal	Category A	Shutdown
116	Time press sensor high	Category A	Shutdown
117	Time press sensor low	Category A	Shutdown
118	Pump press sensor high	Category B	Warning
119	Pump press sensor low	Category B	Warning
121	No engine speed signal	Category C	Warning
122	Manifold air press sensor	Category B	Warning
123	Manifold air press sensor	Category B	Warning
135	Oil Pressure Sensor High	Engine oil pressure sensor is shorted high	Warning	Verify fault simulation not enabled (InPower); inspect sensor and engine harness connector pins; use oil pressure sensor simulator to check control response, replace sensor if it responds; check P7-13, 17, 21 for short (>200k ohms OK) and open (10 ohms or less OK)
141	Oil Pressure Sensor Low	Engine oil pressure sensor is shorted low	Warning	Verify fault simulation not enabled; inspect sensor/harness connector pins; use simulator to check control response; check P7-13, 17, 21 short/open
143	Pre-Low Oil Pres	Engine oil pressure has dropped below the warning trip point	Warning	If powering critical loads, wait until next shutdown period then follow code 415 procedure
144	Coolant Temperature Sensor High	Coolant temperature sensor signal is shorted high	Warning	Verify fault simulation not enabled; inspect sensor/harness pins; use resistive sensor simulator, replace sensor if control responds; check P7-30 (IH20) and P7-34 (IH20 COM) for short to ground and pin-to-pin (>200k ohms OK); compare sensor resistance between pins
145	Coolant Temperature Sensor Low	Coolant temperature sensor signal is shorted low	Warning	Verify fault simulation not enabled; inspect sensor/harness pins; use resistive sensor simulator; check P7-30 and P7-34 for short circuits and compare resistance
146	Pre-High Coolant Temp	Engine operating near cooling system capacity	Warning	Review 151 correction list
151	High Coolant Temp	Coolant temperature has risen above the shutdown trip point	Shutdown	Check coolant level/leaks, airflow obstructions, fan belt, blower fan/circulation pumps; reset and restart
152	Low coolant temp	Category D	Warning	Warning occurs when jacket water coolant temperature is 70 F (21 C) or lower. Check coolant heater power supply (blown fuse or disconnected heater cord); check jacket water coolant level and replenish; look for coolant leakage and repair. In applications where ambient is below 40 F (4 C) Low Coolant Temp may be indicated even though the heaters operate.
153	Manifold air temp sensor	Category C	Warning
154	Manifold air temp sensor	Category C	Warning
155	INTAKE MANIFOLD TEMP HIGH	Intake manifold temperature above normal and has reached the shutdown trip point.	Shutdown	Review the code 151 correction list for other possible causes.
195	COOLANT LEVEL OOR HIGH	Radiator sensor detected coolant level out of range, high.	Warning
196	COOLANT LEVEL OOR LOW	Radiator sensor detected coolant level out of range, low.	Warning
197	Low Coolant Level	Coolant level below warning trip point (optional)	Warning	Follow code 235 procedure at next shutdown
200	LOW OIL PRESSURE	Indicates engine oil pressure has dropped to an unacceptable level.	Warning	If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow 201-SHUTDOWN procedure. Access 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	Set is not operating. Warning occurs when engine coolant temperature is 70° F (21° C) or lower.	Warning	Indicates engine coolant heater is not operating or is not circulating coolant. Check coolant heater power supply, low coolant level, and heater element current draw.
211	HIGH COOLANT TEMP	Indicates the engine coolant temperature is getting close to the recommended maximum temperature limit: 215° F (102° C) − standby or 207° F (97° C) − primary.	Warning	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 212-SHUTDOWN procedure.
212	HIGH COOLANT TEMP	Indicates engine has overheated (coolant temperature above 215° F (102° C) − standby or 207° F (97° C) − primary).	Shutdown	Allow engine to cool down completely. Check for obstructions to cooling airflow; check fan belt; check coolant mixture; check blower fan and circulation pumps on remote radiator installations. Reset control and restart.
213	COOLANT SENDER	Indicates that the resistance of the coolant temperature sender is out of range.	Warning	Check the resistance of the sender. Resistance 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 down completely. Check coolant level in both radiator and coolant recovery bottle and replenish if low. Look for coolant leakage points and repair if necessary.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Shutdown	Allow engine to cool down completely. Check coolant level in both radiator and coolant recovery bottle and replenish if low. Reset control and restart after correcting problem. Shutdown will not occur if genset is in Idle mode (low coolant warning only).
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.
221	FAIL TO CRANK	Indicates possible fault with control or starting system.	Shutdown	Check fuse F3 on the Engine Interface board. Check for poor battery cable connections; clean battery cable terminals and tighten. Recharge or replace a discharged or defective 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 if necessary. Check for dirty or plugged air filter and replace if necessary. Reset the control and restart after correcting the problem.
223	OVERSPEED	Engine has exceeded normal operating speed (115% ±1% of nominal).	Shutdown	Check mechanical fuel linkage and actuator; check governor output module (A38) and digital board (A32).
224	FAIL TO SYNCHRONIZE	Generator set has not synchronized to the system bus within the allowable time frame.	Warning	Check governor system stability; adjust governing and synchronizer parameters; check fuel system.
226	FAIL TO CLOSE	Paralleling breaker has been given a signal to close, but has not closed properly.	Shutdown	Verify breaker charging mechanism; check close signal; verify auxiliary contact signals.
228	Low coolant pressure	Category A	Shutdown
230	LOW DC VOLTAGE	Indicates battery voltage is below 10 VDC.	Warning	Recharge or replace the battery; check the battery charger fuse. Clean and tighten battery cable connections. Check engine DC alternator; replace if normal charging voltage is not obtained. Check float level if applicable.
231	HIGH DC VOLTAGE	Indicates battery voltage exceeds 32 VDC.	Warning	Check float level on battery charger if applicable (lower float level). Check engine DC alternator; replace if normal battery 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.
233	Coolant pressure warning	Category A	Warning
234	Overspeed	Engine speed signal indicates engine speed greater than the shutdown threshold	Shutdown	Cold engine: clear fault and restart; large block load removal: clear and restart; verify fault simulation not enabled; reset threshold via InPower; monitor engine RPM; check electronic governor actuator for binding
235	Low Coolant Level	Coolant level below shutdown trip point (optional)	Shutdown	Check coolant level and leaks; reset and restart
236	Position sensor	Category A	Shutdown
240	LOW FUEL−DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.
241	LOW FUEL	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.
250	EEPROM ERROR	PCC memory error; data corruption of critical operating parameters.	Shutdown	Perform initial start setup procedure; replace digital board (A32) if fault repeats.
251	EEPROM ERROR	PCC memory error; data corruption of noncritical operating parameters.	Warning	Perform adjustment and calibration procedures; replace digital board (A32) if fault repeats.
252	EEPROM ERROR	PCC memory error; data corruption of noncritical operating parameters.	Warning	Verify selected values; repeat save operation; replace digital board (A32) if fault repeats.
253	Oil level alarm	Category D	Shutdown
254	Fuel shutoff valve	Category A	Shutdown
259	Fuel shutoff valve	Category C	Warning
260	CUSTOMER FAULT 1	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Fault functions can be programmed to initiate a shutdown or a warning.
261	GROUND FAULT	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Fault functions can be programmed to initiate a shutdown or a warning.
262	RUPTURE BASIN	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Fault functions can be programmed to initiate a shutdown or a warning.
263	HIGH GEN TEMP	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Fault functions can be programmed to initiate a shutdown or a warning.
265	Fuel temperature sensor	Category C	Warning
266	Fuel temperature	Category A	Shutdown
270	PHASE ROTATION	The phase relationship between the generator set and the system bus is not matched.	Shutdown	Verify genset phase rotation matches bus; verify control wiring to bus PT module.
272	FIRST START	PowerCommand control is not receiving a proper signal from the system master first start sensor.	Warning	Verify Master First Start Sensor and interconnection wiring.
285	ECM PGN TIMEOUT	Datalink failure; PowerCommand 2.3 control not responding to the engine control module.	Shutdown
286	ECM CONFIGURABLE ERROR	Engine control module configuration error - out of calibration.	Shutdown
301	HIGH AC VOLTAGE	One or more phase voltages exceeded 130% of nominal, or exceeded 110% of nominal for 10 seconds.	Shutdown	Check PCC, alternator, excitation circuit, and PT/CT module wiring.
303	LOW AC VOLTAGE	One or more phase voltages dropped below 85% of nominal for 10 seconds.	Shutdown	Check PMG/field wiring, rotating rectifier, load and connectors.
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.
316	Fuel supply pump	Category B	Warning
318	Fuel supply pump	Category B	Warning
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 that a PCC time/current calculation has initiated an overcurrent shutdown.	Shutdown	Check load and load lead connections.

Showing the first 80 of 315 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

Aligning Generator with Engine (Angular Alignment) adjustment

⚠ Accidental starting of the generator set during this procedure presents the hazard of severe personal injury or death.

Tools: Dial indicator, Shims

Disconnect the negative (-) battery cable(s) before beginning.
Fasten a dial indicator to the generator shaft or cooling fan with the sensing point on the capscrew head or flat surface of the drive disc at the bolt circle diameter.
Bar the engine over in a clockwise rotation as viewed from engine flywheel; do not allow it to roll back on compression.
Determine the total indicator reading (T.I.R.) as the sum of the maximum positive and negative dial indicator readings over one revolution.
Measure the distance from the center of the generator shaft to the indicator measuring point.
Measure the distance from the generator side of the flex discs to the center of the generator mounting bolt.
Compare the distances; multiply this ratio times one half the T.I.R. to approximate the amount of shims to remove or add.

Angular Alignment Procedure adjustment

⚠ Accidental starting of the generator set during this procedure presents the hazard of severe personal injury or death. Make sure to disconnect the negative (-) battery cable(s) before beginning.

Tools: Dial indicator, Wooden shims

Disconnect the negative (-) battery cable(s) before beginning.
Fasten a dial indicator to the generator shaft or cooling fan with sensing point on capscrew head or flat surface of drive disc at bolt circle diameter.
Bar the engine over in a clockwise rotation as viewed from engine flywheel; do not allow it to roll back on compression.
Record maximum positive and negative dial indicator readings as the engine completes one revolution.
T.I.R. equals the sum of the maximum positive and negative readings.
Maximum T.I.R. should not be more than .001 inch for each inch of radius.
Remove equal shims from under both generator mounting feet to lower the generator.

Angular Alignment Procedure (Generator to Engine) adjustment

⚠ Accidental starting during this procedure presents the hazard of severe personal injury or death.

⚠ Do not bar engine over by prying on fan blade.

Tools: dial indicator

Disconnect the negative (-) battery cable(s) before beginning.
Fasten a dial indicator to the generator shaft or cooling fan with sensing point resting on the drive disc capscrew head/flat surface at the bolt circle diameter.
Bar the engine over in a clockwise rotation as viewed from the engine flywheel; do not allow it to roll back on compression at the end of travel of each reading.
Record the total indicator reading (T.I.R.) as the sum of the maximum positive and negative dial indicator readings over one engine revolution.
Compare the measured T.I.R. to the maximum allowed (.001 in. per inch of radius from center of shaft to indicator axis); add or remove shims under the generator mounting feet to correct.

Axial Alignment Procedure adjustment

Tools: Dial indicator with holding device (magnetic base or clamp)

Fasten dial indicator holding device to skid base, engine block, or generator shell with magnetic base or clamp.
Position so the sensor point rests on the generator shaft hub.
Bar the engine over clockwise (viewed from engine flywheel) through a couple of rotations.
Record indicator readings in eight equally spaced points around the shaft diameter to provide a T.I.R.
To correct an out-of-tolerance T.I.R., remove capscrews connecting drive discs and flywheel.
Mark the drive discs and flywheel with respect to each other.
Rotate engine or generator so drive disc holes are repositioned 180 degrees from original location.
Reinstall drive disc capscrews and retorque; re-check shaft alignment.
If T.I.R. unchanged, rotate discs to 30, 60, or 90 degrees from original location.
If T.I.R. does not improve, inspect flywheel pilot and drive disc runouts.

Axial Alignment Procedure (Generator to Engine) adjustment

Tools: dial indicator

Fasten a dial indicator holding device to the skid base, engine block, or generator shell with the sensor point resting on the generator shaft hub.
Bar the engine over in a clockwise rotation through a couple of rotations, recording indicator readings at eight equally spaced points around the shaft diameter to obtain axial T.I.R.
Reduce the measured T.I.R. runout by one half if excessive vibration remains after angular alignment.

Bus Voltage Calibration (C) adjustment

⚠ Contacting hazardous voltage components can cause electrocution, resulting in severe personal injury or death.

⚠ Improper calibration or adjustment of the PowerCommand control can cause equipment malfunction or damage.

Tools: Calibrated RMS multimeter (Fluke models 87 or 8060A)

Display the Bus Voltage Calibration submenu.
With all gensets OFF, attach a calibrated voltmeter to TB1-A (L1) and TB1-B (L2) of the bus PT module.
Start another genset and allow it to reach normal operating speed and voltage; connect to the bus.
Calibrate the voltage reading for Bus Volts L1 so display matches the calibrated meter.
Shut the generator set OFF.
Repeat steps 2 through 5 for Bus Volts L2 and L3.
Exit menu to Save changes.

Engine Brake Assembly - Adjust adjustment

⚠ To get maximum brake operating efficiency and to prevent engine damage, follow instructions in this section.

Tools: 3163530 Brake Feeler Gauge - 7.00 mm [0.276 in]

Remove eight capscrews, isolator assemblies, rocker lever cover, and rocker lever cover gasket.
Locate engine brake set marks: BRAKE SET 1-6, 2-5, 3-4.
Rotate engine clockwise until set mark aligns with stamped mark on front gear cover.
Verify both intake and exhaust valves on cylinder are closed and camshaft follower is on inner base circle.
Press engine brake lever down to verify follower contacts camshaft.
Loosen locknut on brake lever adjusting screw and back out one turn.
Insert feeler gauge Part No. 3163530 between bottom of engine brake piston and top of exhaust valve pin.
Tighten adjusting screw until drag on feeler gauge is felt.
Hold adjusting screw and tighten locknut to 20 Nm [15 ft-lb]. Remove feeler gauge.
Repeat on remaining cylinders.
Install rocker lever cover gasket, cover, isolators, and capscrews. Tighten to 25 Nm [18 ft-lb].

Fuel Transfer Pump Control AC Connections (240 VAC to 120 VAC Conversion) adjustment

⚠ The control is set up at the factory for connection to 240 VAC.

Remove the two jumpers between terminals TB1-6 and TB1-7 and 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 120 V.
On the control transformer, remove the two jumpers between terminals H2 and H3 and connect one jumper between H1 and H3 and the other between H2 and H4.
Attach a tag to the control box indicating the supply voltage.

Generator Mount Pre-load Adjustment adjustment

⚠ Accidental starting of the generator set during this procedure presents the hazard of severe personal injury or death. Disconnect the negative (-) battery cable(s) before beginning.

Tools: Two 1 3/4" T x 2" W x 6" L steel spacers, Adequate lifting device

Turn off and disconnect battery charger (if equipped).
Disconnect the negative (-) battery cable(s) to prevent accidental starting.
Unscrew bolt (Item 2) from skid but do not remove from either rear engine vibration isolator.
Loosen the three screws that secure the engine mount brackets to the engine.
Loosen but do not remove the hex nut (Item 1) from the M20 screw of the generator vibration isolators.
Lift the generator until mounting feet brackets are high enough to insert a 1 3/4 inch steel spacer under both stator foot brackets.
Insert spacers and lower the generator so full weight rests on the mounting foot brackets.
Make sure no gap is present between skid and lower mount of rear engine vibration isolators.
Tighten the three screws to secure the bracket to the engine to 190-200 ft-lbs (260-270 N-m).
Lift the generator to remove the two 1 3/4 inch steel spacers.
Start the threads of the rear engine vibration isolator bolts (Item 2) before lowering.
Lower the generator and tighten the two rear engine vibration isolator bolts to 270-330 ft-lbs (365-447 N-m).
Secure the generator foot brackets to the vibration isolators and tighten to 270-330 ft-lbs (365-447 N-m).

Genset Ammeter Display Calibration (B) adjustment

⚠ Contacting hazardous voltage components can cause electrocution, resulting in severe personal injury or death.

⚠ Improper calibration or adjustment of the PowerCommand control can cause equipment malfunction or damage.

Tools: Calibrated RMS multimeter (Fluke models 87 or 8060A)

Display the Current Calibration submenu.
With the genset OFF, attach a calibrated ammeter to L1.
Start the genset and allow it to reach normal operating speed.
Load the genset to maximum rated kVA at rated voltage.
Calibrate the reading for L1 current so display agrees with calibrated ammeter.
Repeat steps 2 through 5 for L2 and L3.
Exit menu to Save changes.

Genset Voltage Display Calibration (A) adjustment

⚠ Contacting hazardous voltage components can cause electrocution, resulting in severe personal injury or death.

⚠ Improper calibration or adjustment of the PowerCommand control can cause equipment malfunction or damage.

Tools: Calibrated RMS multimeter (Fluke models 87 or 8060A)

Display the Voltage Calibration submenu.
With the genset OFF, attach a calibrated voltmeter to the AC output from L1 to L2 (L1 to Neutral for single phase).
Start the genset and allow it to reach normal operating speed.
Calibrate voltage reading for L1 so display agrees with the calibrated voltmeter.
Shut the generator set OFF.
Repeat steps 2 through 5 for L2 and L3.
Exit menu to Save changes.

Governor Calibration Checks adjustment

Tools: Frequency meter or tachometer, Jumper wire

Start the generator set.
Adjust engine no-load speed to the desired allowable speed droop using the Run Speed potentiometer.
With no load, turn GAIN clockwise slowly until engine speed oscillates.
Reduce GAIN slowly counterclockwise until engine speed is stable.
Upset the governor by momentarily shorting terminals 7 and 10 on the governor control.
Apply and remove loads to check generator set response.

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
		12 lead generator sets	Load wires are routed through the CTs	Reconnectable gensets (12 leads) have dual secondary CTs (3 pins); CT wire 2/3 to pin 2 (high voltage) or pin 3 (low voltage).
		6 lead generator sets	Generator output leads are routed through the CTs	Non-reconnectable gensets (6 leads) have single secondary CTs (2 pins).
		Cummins PowerCommand generic AC Reconnect Wiring Diagram 625-2755 (Rev. D) and 625-3100 (Rev. F)		Applies to models DFAA, DFAB, DFAC, DFBF, DFCB, DFCC, DFEB, DFEC, DFFB, DFGA, DFGB, DFJA, DFJB, DFJC, DFJD, DFLB, DFLC, DFLD, DFMB (625-2755) and models DFAA-DFMB plus DFCE, DFED, DQAA, DQAB, DQBA, DQBB (625-3100).
		U, V, W, N terminals (U,V,W = L1,L2,L3; N = L0)	Stranded load wires bolted to generator reconnection terminal block or circuit breaker lugs	Generators can be configured to the nameplate voltages as shown on the Reconnection Diagram decal attached to the backside of the control box cover; many voltages require reconfiguration of the generator output leads.
	A	CT21 – U load leads	A phase	CT dot must face the generator; CT terminal 1 connects to metering circuit; terminal 2/3 connects to ground.
	A (U)	Bus PT module TB1 A	bus A phase	Bus PT module A39.
	A (U)	CT21	U load leads (A phase)	CT dot must face the generator; CT terminal 1 connects to metering circuit, terminal 2/3 to ground.
	B	CT22 – V load leads	B phase	CT dot must face the generator; CT terminal 1 connects to metering circuit; terminal 2/3 connects to ground.
	B (V)	Bus PT module TB1 B	bus B phase	Bus PT module A39.
	B (V)	CT22	V load leads (B phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
	C	CT23 – W load leads	C phase	CT dot must face the generator; CT terminal 1 connects to metering circuit; terminal 2/3 connects to ground.
	C (W)	Bus PT module TB1 C	bus C phase	Bus PT module A39.
	C (W)	CT23	W load leads (C phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
	N	Bus PT module TB1 N	bus neutral	Bus PT module A39.
110/190	3		12	Full load current at Standby rating: 1901 A
110/220	3		12	Full load current at Standby rating: 1642 A
115/230	3		12	Full load current at Standby rating: 1571 A
120/208	3		12	Full load current at Standby rating: 1737 A
139/240	3		12	Full load current at Standby rating: 1505 A
220/380	3		12	Full load current at Standby rating: 951 A
230/400	3		12	Full load current at Standby rating: 903 A
240/416	3		12	Full load current at Standby rating: 868 A
255/440	3		12	Full load current at Standby rating: 821 A
277/480	3	Wye, 4 Wire	12	Full load current at Standby rating: 753 A
277/480	3	Wye, 4 wire	12	Alternator 60 Hz, 12 lead, limited range, 125 °C; single phase power may be taken at up to 40% of nameplate kW at unity power factor
347/600	3		12	Full load current at Standby rating: 602 A
high voltage genset		12-lead CT secondary wire marked 2/3 to pin 2	2/3	For high voltage gensets.
low voltage genset		12-lead CT secondary wire marked 2/3 to pin 3	2/3	For low voltage gensets.

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 QSX15 family

Part #	Description	Category
AF25544	Element, Primary - Air Cleaner - Fleetguard - Heavy Duty	Air filter
AF25545	Element, Safety - Air Cleaner - Fleetguard - Heavy Duty	Air filter
0908-0101	Lead Acid Battery	Battery
3375044	Torque Wrench	Belt
19802521	ECM Dataplate	ECM / ECU
3331096	Cummins, Part No. 3331096	Fuel filter
3376807	Fuel filter	Fuel filter
FS1007	Fleetguard® Nelson®, Part No. FS1007	Fuel filter
M-4376220	Juego Junta Superior N. ° de Pieza	Gasket
M-4376221	Juego Junta Inferior N. ° de Pieza	Gasket
3375049	Oil Filter Wrench	Oil filter
3406810	Combination Full-Flow/Bypass Lubricating Oil Filter Cummins Part No. 3406810	Oil filter
0908-0203	Operator manual	Operator manual
0908-0204	Operator manual	Operator manual
0908-0230	Generator Set Operator Manual	Operator manual
0179-3536	Coolant heater (Revision E)	Service part / kit
0402-0222	Vibration isolator (non-seismic rated, does not carry IBC/OSHPD certification)	Service part / kit
0402-0234	Vibration isolator (non-seismic rated, does not carry IBC/OSHPD certification)	Service part / kit
0402-0246	Vibration isolator (non-seismic rated, does not carry IBC/OSHPD certification)	Service part / kit
0402-0427	Vibration isolator (non-seismic rated, does not carry IBC/OSHPD certification)	Service part / kit
0908-0107	Radiator Information	Service part / kit
0908-0110	Health and Safety (Diesel Generator Sets)	Service part / kit
0908-0219	Alarm Module (option)	Service part / kit
17200015	Engine Shutdown	Service part / kit
17690172	Engine Braking System	Service part / kit
17800006	Engine Model	Service part / kit
3163156	Service cable for InPower™	Service part / kit
3822735	Plastic bead blasting media	Service part / kit
3886301	InPower™ electronic service tool	Service part / kit
A035H139	Switch, Pushbutton	Service part / kit
A040U808	Harness, Control − Door (Includes Items 30 & 31)	Service part / kit
A046Y204	Shield, Wiring	Service part / kit
CC2609	Fleetguard Water-Check H2O 3-Way Test Strips	Service part / kit
M-3685996	Intake Valve	Service part / kit
M-5473065	150mm Kit de Motor M-5473066	Service part / kit
M-5473069	152mm Kit de Motor M-5473070	Service part / kit
M-5473074	Kit de Motor M-5473075	Service part / kit
TB3-5	Generator Set Control Panel Terminal Block	Service part / kit
TB3-6	Generator Set Control Panel Terminal Block	Service part / kit
ol204vt	Torque Peak	Service part / kit
M-5473087	Piston Kit	Piston kit
M-5484414	Piston Pin	Piston pin
M-3686661	Valvula de escape - M-3686661	Valve

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 QSX15-G9?

The Cummins/Onan QSX15-G9 engine has an oil capacity of 83.3 liters.

What is the displacement of the Cummins/Onan QSX15-G9?

The Cummins/Onan QSX15-G9 has a displacement of 15.0 liters with 6 cylinders.

Which generators use the Cummins/Onan QSX15-G9 engine?

The Cummins/Onan QSX15-G9 powers 14 generator set(s), including Cummins/Onan 350DFEG, Cummins/Onan 450 DFEJ, Cummins/Onan 500 DFEK, Cummins/Onan C450D6, Cummins/Onan DFE.

How often should you change the oil in the Cummins/Onan QSX15-G9?

The Cummins/Onan QSX15-G9 oil change interval is every 8 hours.

What is a common problem with the Cummins/Onan QSX15-G9 engine?

A commonly reported issue on generators using the Cummins/Onan QSX15-G9 is: Over Current.