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Cummins/Onan VTA28 Engine

Name: Cummins/Onan VTA28 Engine
Brand: Cummins/Onan

The Cummins/Onan VTA28 is a 28 L turbo charged and after-cooled engine. It powers generator sets from AKSA and Cummins/Onan, including the AC710, DFGB and DFGE. It holds 84 L (22.2 gal) of oil and 167 L (44.1 gal) of coolant.

Also known as: Cummins VTA28

Part of the Cummins/Onan VTA28 engine family — 4 variants share parts & fitment.

28.0 L

Displacement

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
Aspiration	turbo Charged and after-cooled

Generator sets powered by this engine

Shared across brands: AKSA, Cummins/Onan

AKSA AC710 Cummins/Onan DFGB Cummins/Onan DFGE Cummins/Onan VTA28

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

Common problems

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 produces excessive noise during operation.
Cause: Possible causes include: loose or damaged engine components, worn-out bearings, or a malfunctioning muffler.
Fix: Inspect the engine for any loose parts and tighten as necessary. Check the bearings for wear and replace if needed. Test the muffler to ensure it is functioning properly.
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.
Status Indicators are not functioning properly.
Fix: Check the status indicators for any visible damage or loose connections. If the issue persists, refer to the troubleshooting table.
Shutdown After Battle Short will be displayed for this type of shutdown. 1123
Fix: Battle Short is suspended and a shutdown occurs immediately if any of the following critical shutdown faults occur: Overspeed − Fault code 234, Emergency Stop − Fault code 1433, Remote Emergency Stop − Fault code 1434, Speed Signal Lost − Fault code 121, Excitation Fault − Fault code 2335. 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.
Make sure the generator set cooling inlet/outlet and exhaust ventilation openings are clear (not blocked) and operational.
Fix: Remove all loose debris from surrounding area of generator set. Air flow from the radiator fan can blow loose items around and into ventilation openings.
Make sure the fuel tanks have sufficient fuel and that fuel system is primed.
Fix: Check to make sure there are no leaks and that all fittings are tight.
Fail to Start Indicator: This red lamp indicates the engine failed to start.
Fix: To clear a Fail to Start shutdown, place the O/Manual/Auto switch in the O position and press the Fault Acknowledge/Reset button. Before attempting to restart, wait two minutes for the starter motor to cool and then repeat the starting procedure. If the engine does not run after a second attempt, refer to the Troubleshooting section.
Fail To Shut Down is displayed. 1416
Fix: The Fault Acknowledgement/Reset button will clear the fault message, but will remain in the Fault/History file with an asterisk sign (* equals active fault) as long as Battle Short mode is enabled.
Control and diagnostics via network or PC (laptop) are not working.
Fix: Ensure that the network connection is stable and correct. Check the control panel settings for any misconfigurations. Refer to the troubleshooting table if issues continue.
Battle Short Active. 1131
Cause: This feature must only be used during supervised, temporary operation of the genset. The faults that are overridden during Battle Short mode consist of faults that can affect genset performance or cause permanent engine, alternator, or connected equipment damage.

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

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter			—
Fuel filter			—
Oil filter			—
Battery			—
Belt			—
Coolant filter			—
Oil			—
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
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	AVR Droop setting	5	% at full load, 0 PF
Other	AVR voltage regulation (load regulation)	approximately ±0.5	% RMS
Other	B+ output fuse	10	amp	F1, Base board, 12/24 volt
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	Customer Output relay contact rating	2	amps at 30 VDC	TB1 customer outputs 1-4, normally open
Other	GOV GAIN default value for paralleling applications	70	%
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	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 cranking limit	75	seconds	three 15-second cranking cycles with two 15-second rest periods
Other	REG VHZ (underfrequency roll-off) adjustable range	1 through 50; normal range 7 through 21
Other	Start delay adjustment range	0 to 300	seconds
Other	Stop delay adjustment range	0 to 600	seconds
Other	Switched B+ output fuse	5	amp	F2, Base board, 12/24 volt
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
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	K19 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K19 engine normal oil pressure	50-70	psi (345-482 kPa)	normal run
Pressure	K19 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	K38 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K38 engine normal oil pressure	45-65	psi (310-448 kPa)	normal run
Pressure	K38 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	K50 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K50 engine normal oil pressure	50-70	psi (345-482 kPa)	normal run
Pressure	K50 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	L10/M11 engine idle oil pressure	15	psi (103 kPa)	idle
Pressure	L10/M11 engine normal oil pressure	30-50	psi (207-345 kPa)	normal run
Pressure	L10/M11 oil pressure shutdown limit	20	psi (138 kPa)	run mode value
Pressure	L10/M11 oil pressure shutdown limit	8	psi (55 kPa)	idle mode value
Pressure	L10/M11 oil pressure warning limit	12	psi (83 kPa)	idle mode value
Pressure	L10/M11 oil pressure warning limit	25	psi (172 kPa)	run mode value
Pressure	Low oil pressure shutdown	below 14	psi (97 kPa)	time delayed ~10 seconds following starter disconnect
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)

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

Recommended fluids

Fluid	Grade	Standard	Ambient	Capacity	Notes
Coolant	soft water / E.G. / DCA mixture				Cooling system to be filled with soft water/E.G./DCA mixture (on-site review checklist).
Fuel	ASTM No. 2 diesel	ASTM			Alternate diesel fuels per Cummins engine O&M Manual specifications
Fuel	Diesel				Day tank fuel transfer pump maintains reservoir of diesel fuel in the day tank.
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	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.
1122	Rated/Idle Trans		Info
1123	Shutdown After Battle Short	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	Warning status indicator is lit when Battle Short mode is enabled. Refer to Battle Short Mode description in Section 3.
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	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 Out Of Range	Incorrect feature or calibration entered into control.	Shutdown	Reload correct calibration.
1335	Noncrit Scaler Out Of Range	Incorrect feature or calibration entered into control.	Warning	Reload correct calibration.
1337	No Message		Info
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	With Battle Short mode enabled and an overridden shutdown fault occurring, the fault is announced but the genset does not shut down. Refer to Battle Short Mode description in Section 3.
1417	Powr Down Error	Controller cannot power down.	Warning	Indicates that the controller can not power down because of some unknown condition. Possible drain on battery. Contact an authorized service center for service.
143	Pre-Low Oil Pres	Engine oil pressure has dropped to an unacceptable level.	Warning	Indicates engine oil pressure has dropped below the warning trip point. If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow code 415 procedure.
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	Low Coolant Temp	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	Indicates engine coolant heater is not operating or is not circulating coolant. a. Coolant heater not connected to power supply; check for blown fuse or disconnected heater cord. b. Check for low coolant level and replenish if required; look for possible coolant leaks and repair.
1438	Fail To Crank	Engine failed to crank after PCC received a start signal.	Shutdown	Indicates possible fault with control, speed sensing or starting system. 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	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.
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	Engine has begun to overheat.	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	Engine has overheated above the shutdown trip point.	Shutdown	Indicates engine has overheated (coolant temperature above shutdown trip point). Allow engine to cool down completely. a. Check coolant level and replenish if low; look for coolant leaks and repair. b. Check for obstructions to cooling airflow. c. Check fan belt and repair or tighten if necessary. d. Check blower fan and circulation pumps on remote radiator installations. e. Reset control and restart after locating and correcting problem.
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; replenish if low; reset control and restart.
204	OIL PRES SENDER	Indicates that the control has sensed that the engine oil pressure sender is out of its working range.	Warning	Check that the engine oil pressure sender is properly connected.
210	LOW COOLANT TEMP	Warning occurs when engine coolant temperature is 70°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; check air inlets and outlets and remove obstructions to airflow.
212	Oil Temp Sensor H	Indicates engine has overheated (coolant temperature above 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	Check the resistance of the sender; should be 500 to 2k ohms.
214	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Warning	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 leakage points; reset control and restart.
220	MAG PICKUP	Mag pickup speed indication is not being 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 for poor battery cable connections; clean battery cable terminals and tighten. Recharge or replace a discharged or defective 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	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.
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 LOW DC VOLTAGE 230.
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.)	Genset has been in Idle mode too long.	Warning	Indicates genset has been in Idle mode too long (10 minutes maximum).
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.
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

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

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

Tools: Voltmeter, Jumpers, 12 volt battery

Throw the line circuit breaker OFF and shut down the set.
Remove accessory box cover; remove plug P10 from A37 J10.
Prepare to measure output voltage across generator terminals.
Connect 12V battery jumpers to X (P10-6 red) and XX (P10-3 brown).
Check polarity; incorrect polarity makes the test inconclusive.
Start set and connect battery negative to the XX lead.
Rated or higher balanced voltage means generator circuitry is OK.
Unbalanced voltage: troubleshoot main stator; low voltage: exciter/field.

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)

Insulation Resistance (Megger) & Polarization Index (PI) Testing diagnostic

⚠ The windings of medium-voltage (601 through 15,000 volts) generator sets must be dry before the generator is operated.

Tools: Megger or insulation resistance meter, Grounding cluster, High voltage gloves

Perform the Generator Set Grounding Procedure.
Disconnect plug J10 from A37 and AC control leads 4,5,6,7,8.
If RTD option installed, ground all six RTD temperature leads (18 leads).
Perform Insulation Resistance Test and PI Test for desired windings.
Megger test: apply voltage for up to one minute.
PI test: apply voltage for ten minutes; record 1-minute and 10-minute readings.
PI ratio of 2 or greater is good for new and in-service sets.
Investigate and correct low readings before returning set to service.

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 Diodes diagnostic

⚠ Layers of dust can cause diodes to overheat and fail. Brush dust off regularly.

Tools: Ohmmeter

Disconnect the diode pigtails from the terminal posts.
Using an ohmmeter, measure resistance between pigtail and mounting plate.
Reverse meter test probes and repeat the tests.
Resistance should be high in one direction and low in the other.
If high or low in both directions, replace the diode.

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.

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
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
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

114

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
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
960-0630C	PCC2100 PowerCommand Control	controller
0300-4623-18	DFGB (600V)	current_transformer
0300-4623-34	DFGB BR (0-480V)	current_transformer
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 (7/8º ID) (Order By The Foot - 10 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
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	hose
122-0702	Head, Oil Filter	oil_filter
122-0777	Filter, Lube Oil	oil_filter
098-7954	Label, Information − Element Replacement	other_service
102-1335	Plug, Oil Drain	other_service
130-1430	Exchanger, Heat	other_service
130-1515	Tank, Water	other_service
130-4582	Bracket, Mounting	other_service
130-5666-02	Tube, Water Heater	other_service
130-5852-02	Tube, Water Heater	other_service
140-1260	Fitting, Safety Filter	other_service
140-1260-01	Fitting, Safety Filter	other_service
193-0128	Gauge, Fuel Pressure (0-200 Lbs)	other_service
307-2859	Relay, Power - 24VDC (K11)	other_service
323-1491	* Pin, Contact (Used With Inline G)	other_service
323-1492	* Socket, Contact (Used In Stations 18, 19)	other_service
323-1718	* Pin, Contact (Used In Station 17)	other_service
332-2634	Clamp, Retainer 4 Prior To December 1996 Production (Mounted On Top And Side Of Control Box Wrapper)	other_service
333-0639-01	Heater, Coolant (4990 Watt)	other_service
333-0639-02	Heater, Coolant (6420 Watt)	other_service
416-0446	Cable, Battery - Jumper	other_service
504-0171	Valve, Shutoff	other_service
505-0100	Nipple, Pipe - Close (1/2”)	other_service
505-1071	Coupling, Flexible (For 2" Pipe)	other_service
505-1072	Valve, Water	other_service
518-0548-24	Clamp, Retainer Begin December 1996 Production (Mounted On Top And Side Of Control Box Wrapper On The Side Towards The Control Box Cover)	other_service
518-0548-42	Clamp, Retainer 4 Prior To December 1996 Production (Mounted On Top And Side Of Control Box Wrapper)	other_service
898-1254-25	Sleeving – Heater Leads (59”)	other_service
960-0103		other_service
960-0145		other_service
960-0241		other_service
960-0259		other_service
960-0606		other_service
960-0611		other_service
M-CK4911685P	Cylinder Kit	other_service
MCB4911685	Piston Kit	other_service
307-2621-02	Relay, Start Solenoid (K4)	relay
323-1445	* Seal, Cable (Used With Station 17)	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 Level (S7)	sensor
193-0481	Sender Assembly - Low Coolant Level	sensor
193-0529-01	Sensor, Temperature	sensor
309-0269	Switch, Low Engine Temperature (S4)	sensor
960-0504	PCC Control Service Manual	service_manual
960-0507	Detector Control Service Manual	service_manual
309-0649	Thermostat	thermostat
508-0292	Washer, Sealing - Copper	washer

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?

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

What is the displacement of the Cummins/Onan VTA28?

The Cummins/Onan VTA28 has a displacement of 28.0 liters.

Which generators use the Cummins/Onan VTA28 engine?

The Cummins/Onan VTA28 powers 4 generator set(s), including AKSA AC710, Cummins/Onan DFGB, Cummins/Onan DFGE, Cummins/Onan VTA28.

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

A commonly reported issue on generators using the Cummins/Onan VTA28 is: The generator set produces low voltage output.. 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..