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Cummins/Onan VTA28-G7 Engine

The Cummins/Onan VTA28-G7 is a 28 L 12-cylinder turbocharged and aftercooled engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, including the 750DFGE, DFGE and DFGE 60 Hz. It holds 84 L (22.2 gal) of oil and 167 L (44.1 gal) of coolant.

Also known as: Cummins VTA28-G7

Part of the Cummins/Onan VTA28 engine family — 8 variants share parts & fitment.

28.0 L

Displacement

Cylinders

1800 rpm

Rated speed

84.0 L

Oil capacity

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

Engine specifications

Oil capacity	84.0 L
Coolant capacity	167.0 L
Displacement	28.0 L
Cylinders	12
Aspiration	Turbocharged and Aftercooled
Rated speed	1800 rpm

Generator sets powered by this engine

Cummins/Onan 750DFGE Cummins/Onan DFGE Cummins/Onan DFGE 60 Hz

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

Common problems

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. 1442
Fix: See code 441 for corrective action.
The generator set produces low voltage output. 402
Cause: Possible causes include: dirty or clogged air filter, malfunctioning alternator, or a faulty voltage regulator.
Fix: Clean the air filter and check for any blockages. Inspect the alternator for signs of damage or wear. Test the voltage regulator to ensure it is functioning correctly.
The generator set produces high temperature warnings. 403
Cause: Possible causes include: insufficient coolant, malfunctioning thermostat, or a clogged radiator.
Fix: Check the coolant level and top up if necessary. Inspect the thermostat for any signs of failure. Clean the radiator to ensure proper airflow.
The generator set does not start. 401
Cause: Possible causes include: low fuel level, faulty starter motor, or a malfunctioning ignition system.
Fix: Check the fuel level and refill if necessary. Test the starter motor for functionality. Inspect the ignition system for any issues.
Speed Signal Lost — Critical shutdown fault; Battle Short is suspended and a shutdown occurs immediately if this fault occurs. 121
Shutdown After Battle Short — Battle Short is suspended and a shutdown occurs immediately if moving the customer installed Battle Short switch to OFF with an active but overridden shutdown fault or a shutdown fault that was overridden at any time. 1123
Remote Emergency Stop — Critical shutdown fault; Battle Short is suspended and a shutdown occurs immediately if this fault occurs. 1434
Remote E-Stop — Indicates remote Emergency Stop. 1434
Fix: See code 1433 to reset.
Pre-Low Oil Pres — Indicates engine oil pressure has dropped below the warning trip point. 143
Fix: If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow code 415 procedure.
Pre-High Cool Tmp — Indicates engine is operating near cooling system capacity. Increase in load or higher ambient temperature may cause High Coolant Temp (151) shutdown. 146
Fix: Review 151 correction list for other possible causes.
Power Down Error — Indicates that the controller can not power down because of some unknown condition. 1417
Cause: Possible drain on battery.
Fix: Contact an authorized service center for service.
Overspeed — Critical shutdown fault; Battle Short is suspended and a shutdown occurs immediately if this fault occurs. 234
Oil Temp — Indicates engine has begun to overheat (oil temperature has risen to an unacceptable level). 421
Fix: If generator is powering non-critical and critical loads and cannot be shut down, use the following: 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 code 151 procedure and also check engine oil level.
Low Oil Pressure — Indicates engine oil pressure has dropped below the shutdown trip point. 415
Fix: Check oil level. If oil level is low, replenish. Reset control and restart.
Low Coolant Temp — Set is not operating. Warning occurs when engine coolant temperature is 70° F (21° C) or lower. NOTE: 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. 1435
Cause: Engine coolant heater is not operating or is not circulating coolant; Coolant heater not connected to power supply; Low coolant level
Fix: Check for blown fuse or disconnected heater cord and correct as required; Check for low coolant level and replenish if required. Look for possible coolant leaks and repair as required.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan VTA28-G7.

Maintenance schedule

Item	Part #
Air filter	140-3288-02	Amazon eBay
Fuel filter	—
Oil filter	102-1335	Amazon eBay
Coolant	—
Oil	—

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
Battery Electrolyte Level	Check	200 hr		Check level of electrolyte at least every 200 hours of operation.
Crankcase Oil and Filter	Change	250 hr	12 mo	X6: If genset is used for standby applications, change oil every 12 months or 250 hours, whichever comes first.
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	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
Gap	Float switch lift to test open	1/8	inch	below C-clip stop
Other	B+ output fuse	10	amp	F1, Base board, 12/24 volt
Other	Customer Output relay contact rating	2	amps at 30 VDC	TB1 customer outputs 1-4, normally open
Other	Genset frequency / RPM nameplate rating	50 or 60 Hz / 1500 or 1800 RPM
Other	Ground Fault Relay current setting	5 to 1200	amperes	optional GFR
Other	Ground Fault Relay time delay setting	0 to 1	second	optional GFR
Other	Optional control relay (K11/K12/K13) contact rating	10	amps at 600 VAC
Other	Switched B+ output fuse	5	amp	F2, Base board, 12/24 volt
Pressure	Air cleaner element cleaning compressed air	30	psi
Pressure	Engine oil pressure - K19 normal	50-70	psi (345-482 kPa)	run mode
Pressure	Engine oil pressure - K38 normal	45-65	psi (310-448 kPa)	run mode
Pressure	Engine oil pressure - K50 normal	50-70	psi (345-482 kPa)	run mode
Pressure	Engine oil pressure - L10/M11 normal	30-50	psi (207-345 kPa)	run mode
Pressure	Engine oil pressure - NTA 855 normal	35-50	psi (241-345 kPa)	run mode
Pressure	Engine oil pressure - V28 normal	50-90	psi (345-620 kPa)	run mode
Pressure	Engine oil pressure shutdown limit - L10/M11	20	psi (138 kPa)	run mode value
Pressure	Engine oil pressure shutdown limit - L10/M11	8	psi (55 kPa)	idle mode value
Pressure	Engine oil pressure warning limit - L10/M11	12	psi (83 kPa)	idle mode value
Pressure	Engine oil pressure warning limit - L10/M11	25	psi (172 kPa)	run mode value
Pressure	Idle Oil Pressure	20	psi	idle
Pressure	Idle Oil Pressure Shutdown Limit	10	psi	idle
Pressure	Idle Oil Pressure Warning Limit	15	psi	idle
Pressure	Max. Allowable Exhaust Back Pressure	27	in. H2O (6.7 kPa)	6 in. NPT outlet
Pressure	Max. Allowable Exhaust Back Pressure	41	in. H2O (10.2 kPa)	5 in. NPT outlet (DFGB/DFGE), 6 in. NPT outlet (DFLB/DFLC)
Pressure	Max. Fuel Inlet Restriction	4	in. Hg (13.5 kPa)
Pressure	Max. Fuel Return Restriction	6.5	in. Hg (22 kPa)
Pressure	Normal Oil Pressure	50-90	psi
Pressure	Oil Pressure Shutdown Limit	35	psi
Pressure	Oil Pressure Warning Limit	40	psi
Pressure	Radiator cleaning compressed air	35	psi	maximum
Resistance	Battery specific gravity, fully charged	1.260	specific gravity	corrected to 80 F (27 C)
Resistance	Charge battery if specific gravity below	1.215	specific gravity
Resistance	Coolant heater coil resistance	10 to 60	ohms	thermostat closed
Resistance	Coolant temperature sender resistance	500 to 2k	ohms
Resistance	Current transformer (PT) primary	1K-2.5K	ohms
Resistance	Current transformer (PT) secondary	140-225	ohms
Resistance	Exciter stator winding - frame size 4C/4D/4E/4F	0.136	ohms	at 68°F (20°C) + 10%
Resistance	Exciter stator winding insulation resistance	1	megohm	replace if less than
Resistance	Fuel solenoid coil resistance	30	ohms	indicates coil OK
Resistance	Governor actuator circuit resistance	7.5	ohms	indicates OK
Resistance	Harness open-circuit check	10 or less	ohms	OK
Resistance	Harness short-circuit check	more than 200k	ohms	OK
Resistance	Main rotor winding insulation resistance	1	megohm	replace if less than
Resistance	Main stator winding insulation resistance	1	megohm	replace if less than
Resistance	PMG stator resistance	2/6	ohms
Resistance	PMG stator resistance	4.6	ohms
Resistance	PMG stator resistance - frame size HC4	2/6	ohms
Resistance	PMG stator resistance - frame size HC5/HC6/HC7	4.6	ohms
Resistance	PT/CT module 3-ohm resistors	3	ohms	J8-15 to 14, J8-22 to 23, J8-7 to 8
Resistance	Thermistor relay trip point (thermistor chain resistance)	3000 ±500	ohms
Speed	Frequency Adjust range	±5	percent of nominal frequency	example: 60.0 Hz nominal adjustable 57.0-63.0 Hz
Speed	Idle speed adjust	700 to 1100	RPM	default 800 RPM
Speed	Idle speed adjustment	800 ±100	RPM	default 800 RPM
Speed	Overspeed shutdown threshold	115% ±1%	% of nominal
Temperature	Cold Soak for battery CCA rating	0	F	-18 C
Temperature	Engine Cold warning threshold (Code 1435)	70	°F (21°C)	jacket water coolant temperature
Temperature	Engine jacket water coolant heater minimum maintained temperature	90	°F (32°C)	per NFPA 110

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
Fuel	ASTM No. 2 diesel	ASTM			Alternate diesel fuels per Cummins engine O&M Manual specifications
Fuel	Diesel				Do not use zinc coated or copper fuel lines with diesel fuel. Be sure all fuel supplies have a positive shutoff valve.
Fuel	number 2 diesel				Direct injection; automatic electric fuel shutoff
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	81.0 ml	Generator end bearing lubricant; temperature range -22°F to +248°F (-30°C to +120°C); 2.74 oz. (81 ml) equally divided between the bearing, the bearing cap cavity, and the 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
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.
121	SPEED SIGNAL LOST	Mag pickup speed indication is not being sensed.	Shutdown	Restart and check RPM on the digital display.
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.
143	PRE-LOW OIL PRES	Engine oil pressure has dropped to an unacceptable level.	Warning	If critical loads, wait until next shutdown period and follow code 415.
144	COOL SENSOR HIGH	Engine coolant temperature signal is shorted high.	Warning	Check sender/connectors/wires.
145	COOL SENSOR LOW	Engine coolant temperature signal is shorted low.	Warning	Check sender/connectors/wires.
146	PRE-HIGH COOL TMP	Engine has begun to overheat.	Warning	Reduce load; check air inlets/outlets; follow code 151 if engine can be stopped.
151	HIGH COOLANT TEMP	Engine has overheated above the shutdown trip point.	Shutdown	Allow cool down; check coolant level, cooling airflow, fan belt, blower fan and circulation pumps.
197	Low Coolant Level	Optional	Warning	Indicates engine coolant level has fallen below the warning trip point. If generator is powering critical loads and cannot be shut down, wait until next shutdown period, then follow code 235 procedure.
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	Indicates engine has exceeded normal operating speed. (115% ±1% of nominal).	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.
234	OVERSPEED	Engine has exceeded normal operating speed.	Shutdown	Check for large block load removal, flammable vapors or leaking turbocharger seals.
235	Low Coolant Level	Optional	Shutdown	Indicates engine coolant level has fallen below the shutdown trip point. Allow engine to cool down completely. a. Check coolant level and replenish if low; look for possible coolant leakage points and repair. b. Reset control and restart.
240	LOW FUEL−DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.
241	LOW FUEL	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.
250	EEPROM ERROR	Indicates PCC memory error. Data corruption of critical operating parameters.	Shutdown
251	EEPROM ERROR	Indicates PCC memory error. Data corruption of noncritical operating parameters.	Warning
252	EEPROM ERROR	Indicates PCC memory error. Data corruption of noncritical operating parameters.	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.
301	HIGH AC VOLTAGE	Indicates that one or more of the phase voltages has exceeded 130% of nominal, or has exceeded 110% of nominal for 10 seconds.	Shutdown
303	LOW AC VOLTAGE	Indicates that one or more of the phase voltages has dropped below 85% of nominal for 10 seconds.	Shutdown
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.
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.
322	SHORT CIRCUIT	Indicates that generator output current has exceeded 175% of rated.	Shutdown	Check load and load lead connections.
330	OVERLOAD	Indicates that three-phase power output exceeds 105% of standby (or 115% of prime) rating. After five seconds, the Load Dump output is activated. After 60 seconds, the OVERLOAD warning is activated.	Warning	Check load and load lead connections.
335	REVERSE POWER	Indicates improper CT or PT phasing. (Non-parallel units only.)	Shutdown	Check CT / PT wiring. Refer to CT Installation in Section 5.
359	Fail To Start	Engine cranks but fails to start	Shutdown	Indicates possible fuel system or air induction problem. a. Check for empty fuel tank, fuel leaks, or plugged fuel lines. b. Check for dirty fuel filter and replace if necessary. c. Check for dirty or plugged air filter and replace if necessary. d. Reset the control and restart.
415	LOW OIL PRESSURE	Engine oil pressure has dropped below the shutdown trip point.	Shutdown	Check oil level, lines and filters; replenish if low; reset control.
421	Oil Temp	Optional	Warning	Indicates engine has begun to overheat. a. Reduce load if possible by turning off non-critical loads. b. Check air inlets and outlets and remove any obstructions to airflow. If engine can be stopped, follow code 151 procedure and also check engine oil level.
441	LOW BAT VOLTAGE	Battery voltage supply to the control is approaching a low level.	Warning	Recharge or replace battery; check charger fuse, connections and DC alternator.
442	HIGH BAT VOLTAGE	Battery voltage supply is approaching a high level.	Warning	Check battery charger float level; check battery wiring/calibration.
1122	Rated/Idle Trans		Info
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 SHORT ACTIVE	Control is in Battle Short mode.	Warning	Bypasses several critical fault shutdowns for emergency operation.
1311	Customer Input #1	Default display name Customer Fault 1; default status None		The nature of the fault is an optional customer selection (e.g. Low Fuel Day Tank, Water In Fuel, Ground Fault, Low Starting Hydraulic Pressure, Low Starting Air Pressure). Each fault function can be programmed using service tool.
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; default Warning		The nature of the fault is an optional customer selection. Each fault function can be programmed using service tool.
1317	Customer Input #3	Default display name Low Fuel; default Warning		The nature of the fault is an optional customer selection. Each fault function can be programmed using service tool.
1318	Customer Input #4	Default display name Rupture Basin Fault; default Warning		The nature of the fault is an optional customer selection. Each fault function can be programmed using service tool.
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		Info
1416	FAIL TO SHUTDOWN	Genset continues to run after shutdown command.	Warning	Check Battle Short feature enabled condition.
1417	POWER DOWN ERROR	Controller cannot power down.	Warning	Check for possible battery drain.
1433	EMERGENCY STOP	Local Emergency Stop.	Shutdown	Pull button out; move switch to O; press Fault Acknowledge/Reset; select Manual or Auto.
1434	REMOTE E-STOP	Remote Emergency Stop.	Shutdown	See code 1433 to reset.
1435	Engine Cold	Warning LED illuminates when engine jacket water coolant temperature falls below 70°F (21°C); per NFPA 110 requirement, indicates engine may not accept load within 10 seconds	Warning	Check coolant heaters for proper operation; other precautions may be necessary to warm engine before applying load
1438	FAIL TO CRANK	Engine failed to crank after PCC received a start signal.	Shutdown	Check starter, fuse F3, K4 relay, E-Stop switch and MPU circuit.
1442	WEAK BATTERY	Battery voltage at or below weak battery warning trip point during cranking.	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.
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.

Showing the first 80 of 105 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 (750 kW gensets and larger) adjustment

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

⚠ Do not bar engine over by prying on fan blade

Tools: dial indicator

Disconnect negative battery cable(s) before beginning
Fasten dial indicator to generator shaft or cooling fan, sensing point on capscrew head or drive disc flat surface
Bar engine over in clockwise rotation as viewed from flywheel, do not allow roll-back at end of travel
Record total indicator reading (T.I.R.) as sum of max positive and negative readings over one revolution
Calculate shim correction using ratio of generator shaft-to-indicator distance vs generator mounting bolt distance
Add or remove shims from both generator mounting feet as calculated

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 (750 kW gensets and larger) adjustment

Tools: dial indicator

Check axial alignment only when objectionable vibration is present after angular alignment
Fasten dial indicator holding device to skid base/engine block/generator shell, sensor on generator shaft hub
Bar engine over clockwise through a couple of rotations, recording readings at eight equally spaced points
If out of tolerance, remove capscrews connecting drive discs and flywheel, mark discs, reposition holes 180 degrees
Reinstall capscrews and retorque; recheck alignment; try 30/60/90 degree repositioning if unchanged

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.

Generator/Base Board Isolation Procedure diagnostic

⚠ This test involves unregulated excitation of the generator.

⚠ Hazardous voltage; use insulated tools and stand on dry platform.

Tools: Voltmeter, Jumper leads, 12V battery

Throw line circuit breaker OFF and shut down the set.
Disconnect exciter stator leads X and XX from AC harness.
Prepare to measure output voltage across generator terminals.
Bring 12V battery jumpers to X (Field +) and XX (Field -).
Verify polarity is correct before connecting.
Start set; connect battery negative to XX lead.
If rated voltage and balanced phases, generator is OK.
If unbalanced troubleshoot main stator; if low troubleshoot exciter circuits.

Generator/PCC Control Isolation Procedure diagnostic

⚠ This test involves unregulated excitation of the generator; make sure all loads have been disconnected.

⚠ HIGH VOLTAGE: touching uninsulated high voltage parts inside the control box can result in severe personal injury or death.

Tools: 12 volt battery, Jumper leads, Voltmeter

Throw the line circuit breaker OFF and shut down the set.
Remove the accessory box housing cover and remove plug P10 from connector J10 of A37.
Prepare to measure output voltage across the generator terminals while the set is running.
Bring two jumpers from a 12 volt battery for connection to X (Field +) and XX (Field -) pins of plug P10.
Check polarity again; polarity must be correct or the test will be inconclusive.
Start the set and connect the jumper from the battery negative terminal to the XX lead.
If rated output voltage or higher is obtained and all phases are balanced, generator circuitry is probably okay; refer to Section 4.
If voltages are unbalanced, troubleshoot the main stator first; if uniformly low, troubleshoot exciter and field circuits first.

Ground Fault Relay Test diagnostic

Verify N-G Fault Indicator on GFR is not lit; if lit, install bonding jumper at facility service entrance
Move control switch to Run position
Press TEST switch on ground fault relay
Verify control panel warning message displayed and Fault Indicator (>I) lit on GFR
Reset the control panel fault (also resets ground fault relay)

Megger and PI Test diagnostic

⚠ Medium-voltage (601 to 15,000 volts) windings must be dry before the generator is operated.

Tools: Megger or Insulation Resistance Meter, Wheatstone bridge or digital ohmmeter, Grounding Cluster

Perform the Generator Set Grounding Procedure.
Disconnect plug J10 from the voltage regulator output module and the AC control leads (marked 4, 5, 6, 7, 8).
If RTD option installed, ground all six RTD temperature leads (18 leads total).
Perform the Winding Resistance Test for the desired windings.
Perform the Insulation Resistance (Megger) Test and PI Test for the desired windings.
Megger test: apply voltage for up to one minute.
PI test: apply voltage for ten minutes; record resistance at one minute and ten minutes.
PI is the ten-minute reading divided by the one-minute reading; ratio of two or greater is good.

Testing the Float Switch Assembly diagnostic

Tools: Ohmmeter, Feeler gauge

Remove the fuel pump control cover, disconnect the wiring jack and unscrew the assembly from the top of the day tank.
With an ohmmeter, test for electrical continuity between each pair of colored leads while holding the assembly vertical; all readings should be zero.
Lift each float, in turn, to 1/8 inch (3 mm) below the C-clip stop above it and test for continuity; all readings should be infinity.
Use pipe thread sealant when replacing the assembly.

Testing the PMG diagnostic

⚠ HIGH VOLTAGE. Touching uninsulated high voltage parts inside the control and power output boxes will result in severe personal injury or death.

Tools: Wheatstone bridge or digital ohmmeter, Voltmeter, Elbow length insulating gloves

Disconnect plug J10 from the voltage regulator output stage module.
Start the engine at the set and let the speed stabilize.
Measure voltage across lead pairs J10-1 & J10-4, J10-4 & J10-5, and J10-5 & J10-1.
Voltage should be at least 150 VAC for 50 Hz sets and at least 180 VAC for 60 Hz sets, approximately the same for each set of leads.
If voltages are low or uneven, check all leads and connections between A37 and the PMG and repair as necessary.
Stop the set and measure electrical resistance across lead pairs J10-1 & J10-4, J10-4 & J10-5, and J10-5 & J10-1 with a Wheatstone bridge or digital ohmmeter.

Current Transformer (CT) Installation installation

⚠ Improper installation of CT's will cause a 335 Reverse Power shutdown error (non-parallel units only).

Orient the CT dot toward the generator (conventional current flowing into the dot); dot also indicates pin 1 of the CT.
CT21 - U load leads (A phase); CT22 - V load leads (B phase); CT23 - W load leads (C phase).
Route the appropriate leads through each CT: 6-lead gensets route generator output leads; 12-lead gensets route load wires.
For 12 lead (reconnectable) gensets, connect CT secondary wire marked 1 to pin 1; secondary wire marked 2/3 to pin 2 for high voltage or pin 3 for low voltage.
For 6 lead (non-reconnectable) gensets, connect lead from CT terminal #1 to metering circuitry and lead from CT terminal #2/3 to ground.

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	Notes
110 V - 120 V L-N	1	Single phase, 2-wire	PTC module jumper locations
110/190	3	Three Phase Reconnectable
120/208	3	Three Phase Reconnectable
127/220	3	Three Phase Reconnectable
139/240	3	Three Phase Reconnectable
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
220/380	3	Three Phase Reconnectable
240/416	3	Three Phase Reconnectable
254/440	3	Three Phase Reconnectable
277/480	3	Three Phase Non-Reconnectable
277/480	3	Three Phase Reconnectable
347/600	3	Three Phase Non-Reconnectable
380 V - 600 V L-L	3	Three phase	Use PTC module 0300-5382-02; 50/60 Hz

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

Parts cataloged across the Cummins/Onan VTA28 family

119

Part #	Description	Category
140-2301	Cleaner, Air (Includes Replacement Elements) 140−2465	Air filter
140-3288-02	Cleaner, Air	Air filter
140-3349-02	Bracket, Air Cleaner	Air filter
M-1627	BOLT DIAGRAM	Battery
130-3839-01	Guard, Belt − Right Side	Belt
130-3839-02	Guard, Belt − Left Side	Belt
130-3840	Guard, Belt − Top	Belt
130-3841	Guard, Belt − Bottom	Belt
130-3842	Guard, Belt − Front	Belt
130-3843	Guard, Belt − Right Side	Belt
130-3844	Guard, Belt − Bottom Back	Belt
130-3845	Guard, Belt − Top Back	Belt
130-3846	Guard, Belt − Left Side	Belt
511-0105	Belt−V	Belt
M-1761	AIR CLEANERS	Cleaner
EXS-1583-3	CONTROL HEATER	Control heater
960-0630C	PCC2100 PowerCommand Control	Controller
CS-1075-1	COOLANT FILTERS	Coolant filter
CS-1367-2	TYPICAL COOLANT HEATER	Coolant heater
0300-4623-18	DFGB (600V)	Current transformer
0300-4623-34	DFGB BR (0-480V)	Current transformer
ES-1779-1	VOLTAGE REGULATOR AND EXCITATION SWITCH	Excitation switch
FS1304	FILTER	Filter
130-4552	Cover, Coolant Heater	Fluid
333-0407-05	Heater, Oil (300 Watt, 480 Volt)	Fluid
502-1337	Adapter, Coolant Heater	Fluid
FF202	Fuel, Spin-On	Fuel filter
FS1216	Fuel/Water Sep Spin-On	Fuel filter
130-1193	Gasket, Outlet Adapter	Gasket
130-4354	Radiator (Includes Cap, Sight Gauge And Overflow Hose) (Also Includes Cover Plates, Gaskets, Screws And Lock Washers For All Water Outlets)	Gasket
330-0141-04	Gasket, Cover	Gasket
330-0142	Box, Terminal (Includes Cover and Gasket − Ref No. 19 and 20)	Gasket
128-0108	Insulation, Hose – Bulk (Order By The Foot – 12 Feet Required)	Hose
130-3874	Base, Mounting * − Parts Used On Heat Exchanger Installations With Automatic Water Regulator + − Parts Used On Heat Exchanger Installations Without Automatic Water Regulator # − Cut Off And Discard Swivel Connector End Of Hose So That 1/8 NPT Connector End Measures Length As Indicated Above	Hose
130-3875	Tube, Outlet	Hose
130-4576	Tube	Hose
130-4577	Tube	Hose
130-4581	Tube	Hose
416-0680	Cable, Battery (10")	Hose
501-0537-22	Hose, Oil (86”)	Hose
501-0537-23	Hose, Oil (22”)	Hose
501-0744-01	Hose, Coolant	Hose
501-0744-05	Hose, Coolant	Hose
502-0313	Elbow, Hose − 90° (1/8” Pipe to 1/4” Hose)	Hose
502-0395	Connector, Hose	Hose
502-0971	Connector, Hose	Hose
502-1530	Union, Hose (1”) − Nylon	Hose
502-1531	Connector, Hose	Hose
503-0189	Clamp, Hose	Hose
503-0249	Hose − Bulk (Order by the Foot − 3 Feet Required)	Hose
503-0569	Hose (3−1/2” ID) Bulk (Order By The Foot − 2 Feet Required)	Hose
503-0685	Clamp, Hose	Hose
503-0856	Hose, Radiator − Lower (3−1/2” ID x 5−1/2”)	Hose
503-1418	Hose − Bulk (1/4” ID) (Order By The Foot − 18 Feet Required)	Hose
503-1620	Hose – Bulk (3/8" ID) (Order by the Foot)	Hose
503-1634	Hose, Silicon Rubber	Hose
503-1634-01	Hose, Rubber (3/4” ID x 4”)	Hose
503-1728	Hose (3” ID x 5–1/2”)	Hose
503-1779	Hose − Bulk (1” ID) (Order By The Foot − 1 Foot Required)	Hose
503-1870-07	Clamp, Hose	Hose
503-1870-11	Clamp, Hose	Hose
503-1870-12	Clamp, Hose	Hose
503-1870-14	Clamp, Hose	Hose
503-1872-01	Clamp, Hose	Hose
503-1872-05	Clamp, Hose	Hose
503-1872-07	Clamp, Hose	Hose
503-2157-01	Clamp, Hose	Hose
503-2276	Elbow, Hose	Hose
503-2350-04	Hose, Coolant (1” x 5‘)	Hose
503-2350-05	Hose, Coolant (1” x 8‘)	Hose
505-0759	Adapter − Pipe to Hose (1” x 1”)	Hose
518-0548-20	Clamp, Hose	Hose
518-0548-24	Clamp, Hose	Hose
122-0702	Head, Oil Filter	Oil filter
122-0777	Filter, Lube Oil	Oil filter
098-7954	Label, Information − Element Replacement	Service part / kit
102-1335	Plug, Oil Drain	Service part / kit
130-1430	Exchanger, Heat	Service part / kit
130-1515	Tank, Water	Service part / kit
130-4582	Bracket, Mounting	Service part / kit
130-5666-02	Tube, Water Heater	Service part / kit
130-5852-02	Tube, Water Heater	Service part / kit
140-1260	Fitting, Safety Filter	Service part / kit
140-1260-01	Fitting, Safety Filter	Service part / kit
193-0128	Gauge, Fuel Pressure (0-200 Lbs)	Service part / kit
307-2621-02	Relay, Start Solenoid (K4)	Service part / kit
307-2859	Relay, Power - 24VDC (K11)	Service part / kit
323-1491	* Pin, Contact (Used With Inline G)	Service part / kit
323-1492	* Socket, Contact (Used In Stations 18, 19)	Service part / kit
323-1718	* Pin, Contact (Used In Station 17)	Service part / kit
332-2634	Clamp, Hose	Service part / kit
333-0639-01	Heater, Coolant (4990 Watt)	Service part / kit
333-0639-02	Heater, Coolant (6420 Watt)	Service part / kit
416-0446	Cable, Battery - Jumper	Service part / kit
504-0171	Valve, Shutoff	Service part / kit
505-0100	Nipple, Pipe - Close (1/2”)	Service part / kit
505-1071	Coupling, Flexible (For 2" Pipe)	Service part / kit
505-1072	Valve, Water	Service part / kit
518-0548-42	Clamp, Retainer 4 Prior To December 1996 Production (Mounted On Top And Side Of Control Box Wrapper)	Service part / kit
870-0257	Nut, Locking (5/16−18) * − Parts Used On Heat Exchanger Installations With Automatic Water Regulator # − Cut Off And Discard Swivel Connector End Of Hose So That 1/8 NPT Connector End Measures Length As Indicated Above + − Parts Used On Heat Exchanger Installations Without Automatic Water Regulator	Service part / kit
898-1254-25	Sleeving – Heater Leads (59”)	Service part / kit
EXS-1036-1	RAIN CAP	Service part / kit
M-1808-4	TYPICAL INSTALLATION	Service part / kit
M-CK4911685P	Cylinder Kit	Service part / kit
MCB4911685	Piston Kit	Service part / kit
M-1759	INJECTION PUMP	Pump
323-1445	* Seal, Cable (Used With Station 17)	Seal
508-0292	Washer, Sealing - Copper	Seal
151-0411	Pickup, Magnetic	Sensor
193-0432	Sender, Oil Temperature (S2 Engine Block, E4 Oil Pan)	Sensor
193-0444	Sender, Oil Pressure (S1)	Sensor
193-0468	Sender, Low Coolant	Sensor
193-0481	Sender Assembly - Low Coolant Level	Sensor
193-0529-01	Sender, Oil Temperature	Sensor
309-0269	Sender, Temperature-Lo Engine	Sensor
M-1760	PRE-HIGH AND HIGH COOLANT TEMPERATURE SENSOR	Sensor
960-0504	PCC Control Service Manual	Service manual
960-0507	Detector Control Service Manual	Service manual
309-0649	Thermostat (Includes Connector Socket) (S11)	Thermostat

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

Common questions

What is the oil capacity of the Cummins/Onan VTA28-G7?

The Cummins/Onan VTA28-G7 engine has an oil capacity of 84.0 liters.

What is the displacement of the Cummins/Onan VTA28-G7?

The Cummins/Onan VTA28-G7 has a displacement of 28.0 liters with 12 cylinders.

Which generators use the Cummins/Onan VTA28-G7 engine?

The Cummins/Onan VTA28-G7 powers 3 generator set(s), including Cummins/Onan 750DFGE, Cummins/Onan DFGE, Cummins/Onan DFGE 60 Hz.

What is a common problem with the Cummins/Onan VTA28-G7 engine?

A commonly reported issue on generators using the Cummins/Onan VTA28-G7 is: 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.. Fix: See code 441 for corrective action..