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Cummins/Onan NTA-855-G2 Engine

The Cummins/Onan NTA-855-G2 is a 14 L 6-cylinder turbocharged and aftercooled engine rated at 1800 rpm, producing up to 346.9 kW. It powers generator sets from Cummins/Onan, including the 300 DFCB, 300DFCB-2272, 300NTA2 and DBCB. It holds 31 L (8.2 gal) of oil and 20.8 L (5.5 gal) of coolant.

Also known as: Cummins NTA-855-G2

Part of the Cummins/Onan NTA855 engine family — 17 variants share parts & fitment.

14.0 L

Displacement

Cylinders

1800 rpm

Rated speed

346 kW

Gross power

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

Engine specifications

Oil capacity	31.0 L
Coolant capacity	20.8 L
Displacement	14.0 L
Cylinders	6
Aspiration	Turbocharged and Aftercooled
Rated speed	1800 rpm
Gross power	346 kW

Generator sets powered by this engine

Cummins/Onan 300 DFCBCummins/Onan 300DFCB-2272Cummins/Onan 300NTA2Cummins/Onan DBCBCummins/Onan DFCBCummins/Onan DFCFCummins/Onan DFM 300 Cummins/Onan NTA855G2 CP350-6 DFCB

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

Common problems

No AC output voltage.
Fix: 3. Confirm that Exciter Switch is at ON position. Voltage regulator is inoperative. Refer to Initial Start and Checks, and Adjustments sections for voltage check and adjustment procedures. Contact your distributor if voltage build-up is still a problem.
LO FUEL lamp lights. Engine continues to run.
Fix: Check fuel supply and replenish as required.
Engine will not crank.
Cause: Possible fault with control or starting system.
Fix: A. Fault lamp on. Correct fault and reset control. b. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. c. Discharged or defective battery. Recharge or replace the battery. d. Contact your distributor for assistance if none of the above applies.
Engine starts from generator control panel but will not start automatically or from a remote panel.
Cause: (Note: The Run/Stop/Remote switch must be in the Remote position for automatic or remote starting).
Fix: Remote circuit breaker is tripped. Reset breaker and restart. Contact an authorized service center if breaker trips after resetting.
Engine runs and then shuts down, OVERSPEED lamp lights.
Fix: 4. Indicates engine has exceeded normal operating speed. Contact your distributor for service.
UNDER FREQUENCY 313
Fix: Shutdown
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: 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.
Fix: Indicates Run/Stop/Remote switch is in the Stop position which will prevent automatic starting if an automatic transfer switch is used. Move the Run/Stop/Remote switch to the Remote position for automatic starting.
SHORT CIRCUIT 322
Fix: Shutdown
Over Current 1471
LOW OIL PRESSURE 200
Fix: Shutdown
Low Coolant Level 197
LOW AC VOLTAGE 303
Fix: Shutdown
LO OIL PRES lamp lights. Engine shuts down.
Cause: Engine oil pressure has dropped to 12 psi (88 kPa).
Fix: 5. Check oil level, lines and filters. If oil system is okay but oil level is low, replenish. Reset control and restart. Contact your distributor if oil pressure is not in the range of 40 to 70 psi (276 to 483 kPa).
LO FUEL lamp lights. Engine shuts down and LO OIL PRES lamp lights.
Fix: Check fuel level and replenish as required.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan NTA-855-G2.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter			—
Fuel filter			—
Oil filter	8-7-24		—	465 hr
Battery	127 A/hr		—
Belt			—
Coolant		84.8 Litres	—
Oil	38.6 Litres	38.6 Litres	—
Spark plug			—

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

Service intervals

Item	Action	Hours	Months	Notes
Generator set	Inspect	8 hr		Check for oil, fuel, cooling and exhaust leaks; check exhaust system audibly and visually with set running
Genset	Inspect	8 hr		Inspect for oil, fuel, cooling and exhaust system leaks. Check exhaust system audibly and visually with set running (footnote X1).
Air Cleaner	Check	50 hr		Clean if required. Perform more often in dusty conditions (footnote X2).
Air cleaner	Clean	50 hr		Clean if required; more often in extremely dusty conditions
Battery Charging System	Check	50 hr
Charge Air Piping	Check	50 hr
Coolant Heater	Check	50 hr		Column alignment in source table is ambiguous; interval as printed in schedule columns.
Coolant Level	Check	50 hr
Crankcase oil	Change	50 hr		First service — Break-in: drain and replace crankcase oil after first 50 hours on new generator sets
Drive belt tension	Check	100 hr		Visually check belts for evidence of slippage
Exhaust condensation trap	Drain	50 hr
Fuel Level	Check	50 hr
Oil Level	Check	50 hr
Anti-freeze and DCA Concentration	Check	100 hr		Refer to engine operation and maintenance manual for procedure (footnote X5).
Battery level/specific gravity	Check	100 hr
Exhaust Condensate Trap	Drain	100 hr
Fuel Filter(s)	Drain	100 hr		Drain 1 cup or more of fuel to remove water and sediment (footnote X4); refer to engine operation and maintenance manual (footnote X5).
Fuel tanks water/sediment	Drain	100 hr		Drain 1 cup or more of fuel to remove water and sediment
Generator air outlet	Check	100 hr
Water and Sediment from Fuel Tank	Drain	100 hr		Drain 1 cup or more of fuel to remove water and sediment (footnote X4).
Air Cleaner Element	Change	500 hr	12 mo	Perform more often in dusty conditions (footnote X2).
Antifreeze and DCA concentration	Check	250 hr	6 mo
Coolant Filter	Change	500 hr	12 mo	Refer to engine operation and maintenance manual for procedure (footnote X5).
Crankcase Breather	Clean	500 hr	12 mo	Refer to engine operation and maintenance manual for procedure (footnote X5).
Crankcase oil and filter	Change	250 hr	12 mo	First service — Table 7-1. If genset used for prime power, change every 6 months or 250 hours. If standby, change every 12 months or 250 hours, whichever comes first.
Generator assembly	Clean	250 hr	6 mo
Heat exchanger plugs	Check	250 hr	6 mo	If equipped
Starting Batteries	Check	250 hr
Cooling System	Clean	500 hr	12 mo	Refer to engine operation and maintenance manual for procedure (footnote X5).
Fuel Filters	Change	500 hr	12 mo	Refer to engine operation and maintenance manual for procedure (footnote X5).
Radiator Hoses for Wear & Cracks	Check	500 hr	12 mo
Generator bearing	Inspect	1000 hr
Generator bearing	Replace	10000 hr	24 mo	Prime power: every 10,000 hours or two years; standby power: every five years
Rupture basin leak detect switch	Test		12 mo	Some areas may require weekly inspections by safety code.

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 maximum T.I.R.	0.001	inch per inch of radius (center of shaft to indicator axis)	measuring deflection to bolt heads
Clearance	Coolant level below radiator cap opening	about two inches (50 mm)	in (mm)	engine cold
Clearance	Exhaust pipe clearance to combustible wall or partition	12	inches (305 mm)	minimum
Clearance	Exhaust pipe clearance to combustible wall or partition	at least 12 inches (305 mm)	inch
Clearance	Exhaust thimble spacing	9	inch (230 mm)	minimum
Clearance	Float switch assembly float lift clearance below C-clip stop	1/8	inch (3 mm)	use a feeler gauge
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 sensor to gear tooth adjustment	back out one quarter turn	turn	after contacting gear tooth
Clearance	Mounting base surface height above floor	at least 6 inches (152 mm)	inch
Clearance	Vibration isolator base elevation difference	0.25	inch (6 mm)	all isolator bases within this elevation of each other
Clearance	Vibration isolator base elevation variation	0.25	inch (6 mm)	shimmed or grouted
Clearance	Vibration isolator top plate to base clearance	0.25	inch (6 mm)	nominal, or greater
Gap	Air cleaner cleaning nozzle distance	1	inch (25 mm)	at least
Gap	Air cleaner element cleaning nozzle distance	at least 1 inch (25 mm)	inch	low pressure compressed air 30 psi (207 kPa)
Gap	Float switch lift to test open	1/8	inch	below C-clip stop
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	AVR Droop setting	5	% at full load, 0 PF
Other	AVR voltage regulation (load regulation)	approximately ±0.5	% RMS
Other	Air cleaner element solvent soak time	15	minutes	Donaldson D1400 solvent or equivalent
Other	Angular alignment maximum T.I.R.	.001	inch per inch of radius	center of shaft to indicator axis
Other	Angular alignment maximum T.I.R.	.001 inches per inch of radius	in/in	center of shaft to indicator axis
Other	Battery electrolyte specific gravity, charge if below	1.215
Other	Battery electrolyte specific gravity, fully charged (corrected)	1.260		corrected; add 0.004 per 10°F above 80°F (27°C)
Other	Battery specific gravity	1.260	specific gravity	1.225 recommended above 95 F (35 C) ambient; 1.280 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, fully charged	approximately 1.260	specific gravity	at 80 F (27 C)
Other	Breather cleaning compressed air	30	psi	maximum (OSHA)
Other	Control circuit wire size, distance 1000 to 2000 ft (305 to 610 m)	16	gauge stranded copper
Other	Control circuit wire size, distance less than 1000 ft (305 m)	18	gauge stranded copper
Other	Cool-down at idle timer range	0 to 30	minutes
Other	Cooling air inlet size relative to radiator duct outlet	1-1/2	times larger	radiator cooled models
Other	Cycle cranking option	15-second crank, 15-second rest, 3 cycles
Other	Engine belt driven charging alternator output	35	ampere, 24 VDC
Other	Fuel lift height limit	6	feet	(1.8 meters) between fuel lift pump and bottom of dip tube
Other	Fuel pump lifting capacity	5 feet (1.525 m)	feet
Other	Fuel pump maximum lift	5	ft (1.5 m)
Other	Fuel tank capacity for continuous full load operation	36	hours	minimum
Other	GOV GAIN default value for paralleling applications	70	%
Other	Load balance line current tolerance	10	percent of median value	with loads connected
Other	Maximum cranking voltage drop	2	volts	difference between battery and starter terminals while cranking
Other	Maximum sulphated ash content of lubricating oil	1.85	percent
Other	Mounting base surface above floor	6	inches (152 mm)	minimum for servicing
Other	Mounting bolt size	3/4	inch	anchored to floor
Other	Over/Under Frequency Sensor Module - Over Hz Set, 50 Hz nominal	55	Hz	reset 53 Hz
Other	Over/Under Frequency Sensor Module - Over Hz Set, 60 Hz nominal	65	Hz	reset 63 Hz
Other	Over/Under Frequency Sensor Module - Under Hz Set, 50 Hz nominal	45	Hz	reset 47 Hz
Other	Over/Under Frequency Sensor Module - Under Hz Set, 60 Hz nominal	55	Hz	reset 57 Hz
Other	Over/Under Voltage Sensor Module time delay	typically 25 percent, approximately 2.5	seconds
Other	Overcrank crank cycle	15 seconds crank / 15 seconds rest, 80-second limit	seconds
Other	Overcrank cranking limit	75	seconds	three 15-second cranking cycles with two 15-second rest periods
Other	Overcrank cranking limit (standard control)	75	seconds
Other	REG VHZ (underfrequency roll-off) adjustable range	1 through 50; normal range 7 through 21
Other	Rated To Idle delay range	0 to 10	seconds	default = 0; Beginning Version 2.303
Other	Start Delay setting range	0 to 300	seconds	default = 0
Other	Start delay adjustment range	0 to 300	seconds
Other	Stop Delay setting range	0 to 600	seconds	default = 0
Other	Stop delay adjustment range	0 to 600	seconds
Other	Under Frequency Roll Off (UFRO) knee point, 50 Hz units	48 to 49	Hz
Other	Under Frequency Roll Off (UFRO) knee point, 60 Hz units	58 to 59	Hz

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		Balanced coolant mixture of water, antifreeze and coolant additives; refer to Cummins engine Operation and Maintenance Manual			Gensets are shipped with coolant added. Check coolant level before initial start.
Coolant	Ethylene glycol base permanent antifreeze				Precharge coolant filter compatible with plain water and ethylene glycol base coolants; refer to engine manufacturer for methoxy propanal base antifreeze.
Coolant	Water/antifreeze mixture precharged with Diesel Coolant Additive (DCA)	Engine manufacturer's coolant requirements; do not use antifreeze with anti-leak additives		62.0 L	Standard radiator capacity 16.5 gallons (62 L) for 275 DFBF
Coolant	Water/antifreeze mixture with DCA	Permanent type antifreeze per supplier proportion; water clean, low mineral content, free of chloride, sulphate or acid; do not use anti-leak additive antifreeze		15.5 U.S. Gal	Cooling system with standard set mounted radiator; engine only capacity 5.0 U.S. Gal (19 Litres) for NT models, 5.5 U.S. Gal (20.8 Litres) for NTA/NTTA models
Coolant	soft water / E.G. / DCA mixture				Cooling system to be filled with soft water/E.G./DCA mixture (on-site review checklist).
Engine oil		API Class CC/CD		42.0 quarts	Oil capacity with filters (all models)
Engine oil	SAE 5W grade synthetic	API class CC/CD; sulphated ash max 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 -25°C		For ambient consistently below -13 F (-25 C) with no provision to keep engine warm. Do not use petroleum base 5W.
Engine oil	SAE 5W synthetic	API Class CC/CD; 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 -25°C		Extreme cold: consistently below -13 F (-25 C) with no provision to keep engine warm
Engine oil	SAE 20W-40	API Class CC/CD, maximum sulphated ash 1.85 percent	above -32°C	10.5 U.S. Gal	Printed as 'Normal duty -32 F (0 C) and above - SAE 20W-40'. Refer to Cummins Engine Manual for extreme conditions. Do not mix oils of another classification or brand.
Engine oil	10W-30	Multigrade oil meeting API classification	-25°C to 25°C		Oil viscosity grade selection table: -13 to 95 F (-25 to 25 C) = 10W-30
Engine oil	SAE 10W-30	API Class CC/CD, max 1.85% sulphated ash	-23°C to -10°C		Table 5-2; Specification section lists 10W-30 for -13 F to 95 F (-25 C to 35 C)
Engine oil	SAE 15W-40	API Class CC/CD, max 1.85% sulphated ash	above -10°C		Table 5-2: 14 F (-10 C) and above; Specification section: -14 F (-10 C) and above
Fuel		Diesel fuel			Do not use zinc coated or copper fuel lines with diesel fuel. Fuel connection at the engine should be made with an approved flexible line.
Fuel	ASTM No. 2 Diesel				Alternate diesel fuels allowed within engine manual specifications. Do not use galvanized or copper lines, fittings or fuel tanks.
Fuel	ASTM No. 2 Diesel Engine Fuel	Refer to Cummins Engine Manual for analysis limits; will also operate on No. 1 or similar diesel fuels			Never use galvanized fuel lines, fittings or fuel tanks
Fuel	ASTM No. 2 diesel fuel	ASTM No. 2			Cummins engines normally use ASTM No. 2 diesel fuel; they will operate on alternate diesel fuels within the specifications shown in the Cummins engine Operation and Maintenance Manual. Never use galvanized or copper fuel lines, fittings or fuel tanks.
Fuel	Diesel				Day tank fuel transfer pump maintains reservoir of diesel fuel in the day tank.
Fuel	No. 2 Diesel Fuel; Bio-Diesel B5-B20 approved with recommendations	ASTM D975 (post-storage purge fuel)			Bio-diesel not recommended for Emergency Standby RV use (low annual hours, critical start nature).
Fuel	No. 2 diesel (No. 1 acceptable)				Filter or strain fuel as tank is filled; keep tanks full to avoid condensation
Fuel	Number 2 diesel fuel				Direct injection fuel system
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		-30°C to 120°C	81.0 ml	Mobilux No. 2 or Shell Alvania R3; generator end bearing; temperature range -22 F to +248 F (-30 C to +120 C); grease divided between bearing, bearing cap cavity and 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.

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 causes generator build-up to be inhibited and the engine to be governed at 800 RPM.	Warning	Remove ground from engine idle input to return to normal speed and voltage.
102	EMERGENCY STOP	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. Can be reset only at the PCC front panel.
1122	Rated/Idle Trans
1123	Shutdown After BS	Shutdown fault occurred while Battle Short was enabled and then disabled.	Shutdown	Review Fault History and perform corrective action.
1124	Delayed Shutdown	Shutdown fault became active while Delayed Shutdown feature was enabled.	Warning	Review Fault History and perform corrective action.
1131	Battle Sh Active	Control is in Battle Short mode.	Warning	Bypasses several critical fault shutdowns for emergency operation.
121	Speed Signal Lost	Mag pickup speed indication is not being sensed.	Shutdown	Restart and check RPM on the digital display.
1311	Customer Input #1	The nature of the fault is an optional customer selection. Example inputs: Low Fuel Day Tank, Water In Fuel, Ground Fault, Low Starting Hydraulic Pressure, Low Starting Air Pressure, etc.		Enable/disable input (Default: enable); Status, Warning or Shutdown (Default: #1-None, #2 thru #4-Warning); Active closed or open (Default: closed [ground]); change display name up to 19 characters (Default: #1-Customer Fault 1).
1311, 1312, 1317, 1318	CUSTOMER INPUT #1 - #4	Optional customer-selected fault input is active.	Warning	Check external wiring and active input (closed/open) selection.
1312	Customer Input #2	Default display name: Ground Fault.		Configurable input; defaults #2 thru #4 = Warning.
1317	Customer Input #3	Default display name: Low Fuel.		Configurable input; defaults #2 thru #4 = Warning.
1318	Customer Input #4	Default display name: Rupture Basin Fault.		Configurable input; defaults #2 thru #4 = Warning.
1334	Crit Scaler OR	Incorrect feature or calibration entered into control.	Shutdown	Reload correct calibration.
1335	Noncrit Scaler OR	Incorrect feature or calibration entered into control.	Warning	Reload correct calibration.
1337	No Message
135	Oil Pressure Sensor H	Engine oil pressure sender signal is shorted high.	Warning	Check sender/connectors/wires.
141	Oil Pressure Sensor L	Engine oil pressure sender signal is shorted low.	Warning	Check sender/connectors/wires.
1416	Fail To Shutdown	Genset continues to run after shutdown command.	Warning	Check Battle Short feature enabled condition.
1417	Powr Down Error	Indicates that the controller can not power down because of some unknown condition. Possible drain on battery.	Warning	Contact an authorized service center for service.
143	Pre-Low Oil Pres	Indicates engine oil pressure has dropped to an unacceptable level. If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow code 415 procedure.	Warning	If powering critical loads and cannot be shut down, wait until next shutdown period and follow code 415 procedure.
1433	Emergency Stop	Local Emergency Stop.	Shutdown	To reset: pull the button out; move the O/Manual/Auto switch to O; press the front panel Fault Acknowledge/Reset button; select Manual or Auto as required.
1434	Remote E-Stop	Remote Emergency Stop.	Shutdown	See code 1433 to reset.
1435	Low Coolant Temp	Warning occurs when engine coolant temperature is 70°F (21°C) or lower. In applications where the ambient temperature falls below 40°F (4°C), Low Coolant Temp may be indicated even though the coolant heaters are operating.	Warning	Indicates engine coolant heater is not operating or is not circulating coolant. Check that coolant heater is connected to power supply (check for blown fuse or disconnected heater cord). Check for low coolant level and replenish if required; look for possible coolant leakage points and repair as required.
1438	Fail To Crank	Indicates possible fault with control, speed sensing or starting system.	Shutdown	See code 441 for corrective action.
144	Coolant Sensor High	Engine coolant temperature signal is shorted high.	Warning	Check sender/connectors/wires.
1442	Weak Battery	Indicates that during cranking, the battery voltage is at or below the weak battery warning trip point for a time greater than or equal to the weak battery set time.	Warning	See code 441 for corrective action.
1443	Battery Failed	Dead battery - engine will not start.	Shutdown	See code 441 for corrective action.
1444	KW Overload	Generator output power exceeded 105% of genset rating.	Warning	Check load and load lead connections; check CTs.
1445	Short Circuit	Generator output current has exceeded 175% of rated.	Shutdown	Check load and load lead connections.
1446	High AC Voltage	One or more phase voltages exceeded 130% of nominal.	Shutdown	Check fault simulation, load removal, threshold settings, Base board/generator.
1447	Low AC Voltage	Phase voltages dropped below 85% of nominal for 10 seconds.	Shutdown	Check overload, output terminal connections, PMG/field wiring, rectifier diodes.
1448	Under Frequency	Engine speed dropped below 90% of nominal for 10 seconds.	Shutdown	Check fuel supply, intake air supply and load.
1449	Over Frequency	Frequency is 10% above base frequency for 20 seconds.	Warning	Check fuel or air delivery; check connections.
145	Coolant Sensor Low	Engine coolant temperature signal is shorted low.	Warning	Check sender/connectors/wires.
1452	Gen CB Not Close	Genset circuit breaker (S2) failed to close when PTC is enabled.	Warning	Refer to Section 5 troubleshooting charts.
1453	Gen CB Not Open	Genset circuit breaker (S2) failed to open when PTC is enabled.	Warning	Refer to Section 5 troubleshooting charts.
1459	Reverse Power	Improper CT phasing.	Shutdown	Check wiring to voltage sense circuit; refer to CT Installation in Section 6.
146	Pre-High Coolant Temp	Indicates engine has begun to overheat (coolant temperature has risen to an unacceptable level).	Warning	Reduce load; check air inlets/outlets; follow code 151 if engine can be stopped.
1461	Loss Of Field	Loss of field (electric) due to reverse kVAR.	Shutdown	Check excitation circuit.
1466	Modem Failure	Control cannot communicate with the modem.	Warning	Check for open, short to ground and loose connections to the modem.
1468	Network Error	Momentary loss of communication from the LonWorks Network.	Warning	Refer to LonWorks Network publications.
1469	Speed/Hz Match	Measured speed and measured AC output frequency do not agree.	Shutdown	Check calibration file.
1471	Over Current	Generator output current exceeded 110% of rated for 60 seconds.	Warning	Check load and load lead connections.
1472	Over Current	Output current exceeded 110% of rated and time/current calculation initiated shutdown.	Shutdown	Check load and load lead connections.
151	High Coolant Temp	Indicates engine has overheated (coolant temperature has risen above the shutdown trip point). Allow engine to cool down completely before proceeding.	Shutdown	Check coolant level and replenish if low; look for coolant leakage points and repair. Check for obstructions to cooling airflow. Check fan belt and repair or tighten if necessary. Check blower fan and circulation pumps on remote radiator installations. Reset control and restart after correcting problem.
197	Low Coolant Level	Indicates engine coolant level has fallen below the warning trip point (optional).	Warning	If powering critical loads and cannot be shut down, wait until next shutdown period, then follow code 235 procedure. If engine can be stopped, follow code 235 procedure.
200	LOW OIL PRESSURE	Indicates engine oil pressure has dropped to an unacceptable level.	Warning	If powering critical loads, wait until next shutdown period then follow 201 procedure.
201	LOW OIL PRESSURE	Indicates engine oil pressure has dropped below the shutdown trip point.	Shutdown	Check oil level, lines and filters; replenish if low; reset control and restart; contact service center.
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. Contact service center.
210	LOW COOLANT TEMP	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; check air inlets/outlets and remove obstructions.
212	Oil Temp Sensor H	Indicates engine has overheated (coolant temperature has risen above the shutdown trip point: 215 F (102 C) - standby or 207 F (97 C) - primary).	Warning	Check sender/connectors/wires.
213	Oil Temp Sensor L	Resistance of the coolant temperature sender is out of range.	Warning	Contact an authorized service center.
214	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Warning	Check coolant level in radiator and coolant recovery bottle; replenish if low; look for leaks.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Shutdown	Allow engine to cool; check coolant level and replenish; look for leaks and repair; reset and restart. Shutdown will not occur in Idle mode.
220	MAG PICKUP	Mag pickup speed indication not sensed or does not match generator set output frequency.	Shutdown	Restart and check RPM; check PCC model setting; inspect and test MPU.
221	FAIL TO CRANK	Possible fault with control or starting system.	Shutdown	Check fuse F3 on the Engine Interface board; check battery cable connections; recharge or replace the battery.
222	OVERCRANK	Possible fuel system problem.	Shutdown	Check for empty fuel tank, leaks, plugged fuel lines; replace dirty fuel or air filter; reset and restart.
223	OVERSPEED	Indicates engine has exceeded normal operating speed. (115% ±1% of nominal).	Shutdown	Contact an authorized service center.
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.
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	Lower battery charger float level if applicable; check engine DC alternator.
232	WEAK BATTERY	Indicates battery voltage drops below 60% of nominal for two seconds, during starting.	Warning	See Warning message 230, LOW DC VOLTAGE.
2327	PTC Fault	PTC module or communication link is not working properly.	Warning	Check PTC module power, ground shield, cycle control power.
2329	Low S1 Frequency	Low utility (S1) frequency.	Warning	Check S1 AC inputs and wiring to PTC at TB5; check sensor set points.
2331	Low S1 Voltage	Low utility (S1) voltage.	Warning	Check S1 AC inputs and wiring to PTC at TB5; check pickup/dropout set points.
2335	Excitation Fault	Loss of all three voltage sense leads or failure in excitation circuit.	Shutdown	Check field wiring (X1 and X2) for shorts or opens.
2336	Memory Error	Control memory error; data corruption of critical operating parameters.	Shutdown	Try reloading calibration file.
2337	Pwr Tran Disabled	PTC module available but PTC feature not enabled.	Warning	Enable PTC feature with InPower; cycle control power.
2338	Pwr Tran Failure	Control could not communicate with the PTC module.	Warning	Check PTC module power and cable ground shield; cycle control power.
2339	Pwr Down Enabled	Power Down (sleep) enabled but PTC module or network board is active.	Warning	None required.
234	Overspeed	Engine has exceeded normal operating speed.	Shutdown	Check for large block load removal, flammable vapors or leaking turbocharger seals.
2341	High Control Temp	Control temperature above 158 F (70 C) for longer than set time.	Warning	Check genset room air flow.
2342	Too Long In Idle (10 min.)	Indicates genset has been in Idle mode too long (10 minutes maximum).	Warning	Exit idle mode.
235	Low Coolant Level	Indicates engine coolant level has fallen below the shutdown trip point (optional). Allow engine to cool down completely before proceeding.	Shutdown	Check coolant level and replenish if low; reset control.
2358	High S1 Voltage	Utility (S1) voltage increased above the over-voltage threshold.	Warning	Measure S1 AC inputs at PTC module; check sensor set points.
2396	S1 CB Not Close	Utility contact (S1) failed to close with PTC enabled.	Warning	Refer to Section 5 troubleshooting charts.
2397	S1 CB Not Open	Utility contact (S1) failed to open with PTC enabled.	Warning	Refer to Section 5 troubleshooting charts.
240	LOW FUEL−DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.

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 Values/Parameters (PCC Adjust Menu) adjustment

Press the button next to the arrow symbol in the display until the + and - symbols are displayed.
If necessary, press the button next to the arrows to move to the numeric character to change.
Press + to increase the value or select the parameter; press - to decrease the value or select the parameter.
Press the save symbol to save changes; changes are not saved if Home or Previous Main Menu is pressed first.

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 (750 kW Gensets and Larger) 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.

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

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 drive disc flat surface at bolt circle diameter.
Bar the engine over clockwise as viewed from the engine flywheel; do not allow it to roll back on compression.
Total indicator reading (T.I.R.) is the sum of the maximum positive and negative readings as the engine completes one revolution.
To lower the generator, remove equal shims from under both generator mounting feet; approximate shim amount from the distance ratio.

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, Magnetic base or clamp

Check axial alignment only when an objectionable vibration is present after angular alignment.
Fasten dial indicator holding device to skid base, engine block, or generator shell with a magnetic base or clamp; rest sensor on generator shaft hub.
Bar the engine over clockwise through a couple of rotations; record indicator readings at eight equally spaced points around the shaft diameter.
To correct out-of-tolerance T.I.R., remove the drive disc capscrews, mark discs and flywheel, rotate 180 degrees from original location, retorque, and recheck.
If unchanged, rotate the discs to 30, 60 or 90 degrees from their original location.

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.

Electric Governor Preliminary Adjustment adjustment

Tools: Frequency meter or tachometer

Idle Speed potentiometer: turn counterclockwise 20 turns, then clockwise 10 turns (mid position).
Run Speed potentiometer: turn counterclockwise 20 turns, then clockwise 10 turns (mid position).
Gain potentiometer: turn screw fully counterclockwise.
Droop potentiometer: fully counterclockwise for isochronous, approx. 40 for 3 percent droop, approx. 80 for 5 percent droop.

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.

Governor Gain Adjustment adjustment

Tools: Frequency meter or tachometer

Close main line circuit breaker and apply approximately 1/4 of rated load.
Make sure engine speed is constant.
Turn Gain potentiometer clockwise slowly until engine speed is not constant.
Slowly turn potentiometer counterclockwise until constant speed is achieved.
Turn potentiometer counterclockwise an additional 1/2 division.

HC4-7 Axial Alignment Procedure adjustment

Tools: Dial indicator with magnetic base or clamp

Check only when an objectionable vibration is present.
Fasten dial indicator holding device to skid base, engine block, or generator shell with magnetic base or clamp.
Position sensor point on the generator shaft hub.
Bar the engine over in a clockwise rotation as viewed from engine flywheel through a couple of rotations.
Record indicator readings in eight equally spaced points around the shaft diameter.
Remove the capscrews connecting drive discs and flywheel and mark discs and flywheel.
Rotate engine or generator so drive disc holes are repositioned 180 degrees from original location.
Put capscrews back in and retorque. Recheck shaft alignment.
If runout 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.

P7 Axial Alignment Procedure adjustment

Check only when an objectionable vibration is present.
Remove the capscrews connecting drive discs and flywheel.
Mark the drive discs and flywheel with respect to each other.
Rotate engine or generator so drive discs holes are repositioned two bolt holes from original location.
Put capscrews back in and retorque. Recheck/record vibration levels.
Repeat this test until drive disc holes are repositioned 180 degrees from original location.
Review vibration data and position drive disc in lowest recorded level location.

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).
	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 (V)	CT22	V load leads (B phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
	C (W)	CT23	W load leads (C phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
110 V - 120 V L-N	1	Single phase, 2-wire		PTC module jumper locations
110/190	3	Wye	12-lead generator
110/220	1	Double delta (single phase)	12-lead generator
115/200	3	Wye	12-lead generator
115/230	1	Double delta (single phase)	12-lead generator
120/208	3	Wye	12-lead generator
120/240	1	Double delta (single phase)	U1, V1, W1, U2, V2, W2, U5, V5, W5, U6, V6, W6	Single phase, double delta connection will reduce set rating and may not work with 3-phase meters
127/220	3	Wye	12-lead generator
139/240	3	Wye	12-lead generator
190 V - 240 V L-L	3	Three phase		Use PTC module 0300-5382-01; 50/60 Hz
200 V - 240 V L-L	1	Single phase, 3-wire		PTC module jumper locations
200/346	3	Wye	12-lead generator
220/380	3	Wye (High/Low Wye)	12-lead generator	60 Hz and 50 Hz listed
230/400	3	Wye	12-lead generator	60 Hz and 50 Hz listed
240/416	3	Wye	12-lead generator	60 Hz and 50 Hz listed
254/440	3	Wye	12-lead generator	60 Hz and 50 Hz listed
277/480	3	Wye	12-lead generator
380 V - 600 V L-L	3	Three phase		Use PTC module 0300-5382-02; 50/60 Hz
Medium voltage (601V to 15kV)	3	6 lead generator	6-lead generator	Drawing number 3052056 (sht. 2) pertains to medium voltage, 6 lead generators, where applicable

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 NTA855 family

Part #	Description	Category
122-0526	Bypass Hood, Air Inlet (Used on Heavy Duty Air Cleaner)	Air filter
140-1346	Air Cleaner (Includes Element)	Air filter
140-2391	Element - Air Cleaner (Standard)	Air filter
140-2392	Element, Air Cleaner - Primary	Air filter
140-2393	Element, Air Cleaner - Safety	Air filter
511-0084	Belt, Charging Alternator	Belt
511-0160	Belt, Drive - V (Fan)	Belt
319-2236	Bracket, Mounting	Bracket
518-0548-58	Clamp, Hose	Clamp
130-3537	CE 1 130-3541 3318318 CE 1 4 501-0551 1 5 503-1467-07 1 503-0189 2 505-0022 1 502-0827	Coolant filter
130-3541	Filter, Water - w/Corrosion Inhibiting Chemical DCA4 (Pre-Charging)	Coolant filter
0300-4623-09	DFCB (600V)	Current transformer
0300-4623-10	DFCC (600V)	Current transformer
0300-4623-24	DFCB BR (0-480V)	Current transformer
0300-4623-27	DFCC BR (0-480V)	Current transformer
155-2287-02	Gasket, Flange (used with 155-2281 Elbow)	Gasket
501-0551	Line, Fuel - Flexible (Bypass line)	Hose
503-1467-07	Hose, Rubber (3/4" ID x 33" LG) Radiator to Filter Housing	Hose
503-1679-02	Hose, Rubber - Upper	Hose
505-1414-01	Hose, Rubber - Lower	Hose
122-0755	Lube & Bypass Filter (Latest Style Used In Engine Manufacturing)	Oil filter
LF3000	Lube, Spin-On	Oil filter
100-1359	Engine, Replacement (Cummins NTA855G)	Service part / kit
102-1335	Plug, Oil Drain	Service part / kit
305-0813-02	CUMMINS battery charger 208VAC/24VDC/10A	Service part / kit
307-2621-02	Relay, Start Solenoid (K4)	Service part / kit
309-0437	(222"F)	Service part / kit
504-0011	Valve, Shutoff (1/2”)	Service part / kit
505-0019	Bushing, Pipe - Reducer 1/2” to 3/8”, DFBF (1/2” to 3/8”) 505-0131 DFCB, DFCC, DFCE (3/4” to 3/8”)	Service part / kit
505-0100	Nipple, Pipe - Close (1/2”)	Service part / kit
526-0029	*Washer, Flat (1/2")	Service part / kit
526-0219	Washer, Flat (1/2)	Service part / kit
800-0048	Screw, Cap - Hex Head (3/8-16 x 3/4”)	Service part / kit
800-0092	Screw, Cap - Hex Head (1/2-13 x 1.5)	Service part / kit
850-0050	Washer, Lock - Spring (3/8”)	Service part / kit
870-0212	Nut, Locking (1/4-20)	Service part / kit
903-0124	NA	Service part / kit
903-0204	NA	Service part / kit
903-0500	NA	Service part / kit
903-0604	NA	Service part / kit
E204747	Coolant heater 240/480V 6420W 1PH	Service part / kit
508-0292	Washer, Sealing - Copper	Seal
151-0411	Pickup, Magnetic	Sensor
193-0244	Sender, Pressure - 0i1	Sensor
193-0375	# Sender, Water Temperature	Sensor
193-0432	Sender, Oil Temperature (S2 Engine Block, E4 Oil Pan)	Sensor
309-0179	Switch, High Water Temperature	Sensor
309-0269	Sender, Temperature-Lo Engine	Sensor
333-0407	Switch, Pressure - Oil, 14# PSI (SHUTDOWN) With Dual Terminals	Sensor
960-0504	PCC Control Service Manual	Service manual
960-0507	Detector Control Service Manual	Service manual

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 NTA-855-G2?

The Cummins/Onan NTA-855-G2 engine has an oil capacity of 31.0 liters.

What is the displacement of the Cummins/Onan NTA-855-G2?

The Cummins/Onan NTA-855-G2 has a displacement of 14.0 liters with 6 cylinders.

Which generators use the Cummins/Onan NTA-855-G2 engine?

The Cummins/Onan NTA-855-G2 powers 8 generator set(s), including Cummins/Onan 300 DFCB, Cummins/Onan 300DFCB-2272, Cummins/Onan 300NTA2, Cummins/Onan DBCB, Cummins/Onan DFCB.

What is a common problem with the Cummins/Onan NTA-855-G2 engine?

A commonly reported issue on generators using the Cummins/Onan NTA-855-G2 is: No AC output voltage.. Fix: 3. Confirm that Exciter Switch is at ON position. Voltage regulator is inoperative. Refer to Initial Start and Checks, and Adjustments sections for voltage check and adjustment procedures. Contact your distributor if voltage build-up is still a problem..