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Cummins/Onan 4BT3.3 Engine

Name: Cummins/Onan 4BT3.3 Engine
Brand: Cummins/Onan

The Cummins/Onan 4BT3.3 is a 3.3 L 4-cylinder turbocharged engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, including the C25 D6, C30 D6, C35 D6 and C40 D6. It holds 7.9 L (2.1 gal) of oil.

Also known as: Cummins 4BT3.3

Part of the Cummins/Onan 4BT3.3 engine family — 4 variants share parts & fitment.

3.3 L

Displacement

Cylinders

1800 rpm

Rated speed

7.9 L

Oil capacity

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

Engine specifications

Oil capacity	7.9 L
Displacement	3.3 L
Cylinders	4
Aspiration	Turbocharged
Rated speed	1800 rpm

Generator sets powered by this engine

Cummins/Onan C25 D6 Cummins/Onan C30 D6 Cummins/Onan C35 D6 Cummins/Onan C40 D6 Cummins/Onan C50 D6 Cummins/Onan C55 D5 Cummins/Onan C60 D6

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

Common problems

Weakness and Sleepiness
Fix: IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired.
Vomiting
Fix: IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired.
Oil Pressure Sensor OOR - Low Code 141
Oil Pressure Sensor OOR - High Code 135
Muscular Twitching
Fix: IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired.
Low Battery Voltage Code 441
Inability to Think Coherently
Fix: IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired.
High Battery Voltage Code 442
Fuel contact with hot engine or exhaust
Fix: Do not permit any flame, cigarette, pilot light, spark, arcing equipment, or other ignition source near the generator set or fuel tank. Fuel lines must be adequately secured and free of leaks. Use an approved flexible line for fuel connection at the engine. Do not use copper piping on flexible lines as it will become brittle if continuously vibrated or repeatedly bent. Ensure all fuel supplies have a positive shutoff valve.
Exhaust gases are deadly
Fix: Provide an adequate exhaust system to properly expel discharged gases away from enclosed or sheltered areas, and areas where individuals are likely to congregate. Visually and audibly inspect the exhaust system daily for leaks per the maintenance schedule. Ensure that exhaust manifolds are secured and not warped. Do not use exhaust gases to heat a compartment. Make sure the unit is well ventilated.
Engine Speed High (Shutdown) Code 234
Engine Oil Pressure Low (Warning) Code 143
Engine Oil Pressure Low (Shutdown) Code 415
Engine Fail to Start Code 359
Engine Coolant Temperature OOR Low (Warning) Code 144

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan 4BT3.3.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	Heavy Duty air filter		0140-3765		Amazon eBay
Fuel filter	Replace fuel filter as needed.		—	500 hr
Oil filter	oil filter element		—	200 hr
Battery			—
Belt			—
Coolant		7.2 l	—
Coolant filter			—
Oil	crankcase oil	10.9 L	—	200 hr
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
Exhaust system	Inspect	8 hr		Visually and audibly inspect the exhaust system daily for leaks per the maintenance schedule; check for corrosion, obstruction, and leaks every time you start the generator set and every eight hours when you run it continuously
Air cleaner restriction indicator	Check	24 hr		If service indicator shows red, replace air cleaner elements and reset indicator.
Coolant heater	Check	24 hr		Verify power and operation; check for leaks.
Coolant level of radiator(s)	Check	24 hr		Top up with Cummins recommended coolant mix if low.
Engine oil level	Check	24 hr		Top up with recommended oil if low.
Fuel level in fuel tank	Check	24 hr		Refill as required.
Fuel lines and hoses	Check	24 hr		Check for leaks, worn or damaged hoses.
Generator set enclosure	Inspect	24 hr		Walk-around; ensure no inlets/outlets covered.
Operator panel operation	Check	24 hr		Check display; replace component if not functioning.
Air intake system for leaks	Inspect	50 hr		Visually inspect; check audibly when running.
Battery connections	Check	50 hr		Verify connections are secure.
Charge alternator	Check	50 hr		Check visually and audibly when running.
Coolant lines and radiator hoses	Check	50 hr		Check for leaks, wear, and cracks.
Cooling fan blades	Inspect	50 hr		Visually inspect through guarding.
Drive belt condition and tension	Check	50 hr		Check for wear or slippage.
Exhaust components and hardware	Check	50 hr		Visually inspect; check audibly when running.
Radiator air flow	Inspect	50 hr		Check for blockage, debris, wear or damage.
Engine oil and filters	Replace	200 hr		First service — After the initial 50 hour interval and every 200 hours thereafter (footnote 3).
Fuel filter and water separator	Replace	500 hr
Cooling system coolant	Replace		24 mo

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
Gap	MPU sensor tip to ring gear teeth clearance	0.5 - 0.6	mm
Other	AFLEX-H (shake table test datum)	<=3.200	g	AC156, tri-axial, 5% damping SRS
Other	AFLEX-V (shake table test datum)	<=1.333	g	AC156, tri-axial, 5% damping SRS
Other	ARIG-H (shake table test datum)	<=2.400	g	AC156, tri-axial, 5% damping SRS
Other	ARIG-V (shake table test datum)	<=0.533	g	AC156, tri-axial, 5% damping SRS
Other	Flywheel teeth (Teeth Pulses Per Revolution)	110		PCC setting
Other	Glow plug preheat time	5		glow plug calibration
Other	Glow plug total glow plug time	60		glow plug calibration
Other	Ground snow load limit	30	psf	For indoor (covered) and outdoor (exposed) installation
Other	Horizontal design seismic coefficient (z/h = 0.0)	1.440	g	Certified seismic design level, IBC Importance IP <= 1.5, Soil Classes A-E, Risk Categories I-IV, Design Categories A-F, SDS <= 2.000 g
Other	SDS (g) at z/h=1 for C10 D6 - C60 D6	2.0	g	Certified SDS, z/h = 1
Other	SDS (g) at z/h=1 for C50 D6C - C125 D6C	2.5	g	Certified SDS, z/h = 1
Other	Speed/frequency mismatch threshold	2.0	Hz	PCC setting
Other	Speed/frequency mismatch threshold time	1.5	seconds	PCC setting
Other	ZPA-H (shake table test datum)	<=2.160	g	AC156, tri-axial, 5% damping SRS
Other	ZPA-V (shake table test datum)	<=0.480	g	AC156, tri-axial, 5% damping SRS
Resistance	Battery ground connection resistance	more than 1	Ohm	indicates repair needed
Resistance	Coolant heater coil resistance	10 to 60	ohms	closed heater
Resistance	Coolant temperature sensor resistance	540 Ohms at -40 F to 1100 Ohms at 100 F; 1100 Ohms at 100 F to 1800 Ohms at 230 F	Ohm
Resistance	Diode reverse direction resistance (good)	above 20	MOhm	reverse direction at 1000 VDC
Resistance	Injection pump actuator resistance	2.3	ohms
Resistance	Main rotor resistance	0.415	Ohms	within 10% of value
Resistance	Main rotor resistance	0.437	Ohms	within 10% of value
Resistance	Main rotor resistance	0.465	Ohms	within 10% of value
Resistance	Main rotor resistance	0.545	Ohms	within 10% of value
Resistance	Main rotor resistance	0.551	Ohms	within 10% of value
Resistance	Main rotor resistance	0.657	Ohms	within 10% of value
Resistance	Main rotor resistance	0.67	Ohms	within 10% of value
Resistance	Main rotor resistance	0.708	Ohms	within 10% of value
Resistance	Main rotor resistance	0.857	Ohms	within 10% of value
Resistance	Main rotor resistance	0.89	Ohms	within 10% of value
Resistance	Main rotor resistance	0.983	Ohms	within 10% of value
Resistance	Main rotor resistance	0.99	Ohms	within 10% of value
Resistance	Main stator winding resistance	0.3	Ohms
Resistance	Main stator winding resistance	0.353	Ohms
Resistance	Main stator winding resistance	0.51	Ohms
Resistance	Main stator winding resistance	0.625	Ohms
Resistance	Main stator winding resistance	0.95	Ohms
Resistance	Main stator winding resistance	1.33	Ohms
Resistance	Main stator winding resistance	1.908	Ohms
Resistance	Starter solenoid wiring continuity (relay 87 to SW)	less than 5	Ohm
Resistance	Stator insulation resistance	1.0	Meg-Ohm	minimum to Earth (Ground)
Resistance	Temperature sender harness lead resistance	less than 0.5	Ohm	each lead from connection to PCC
Resistance	Varistor resistance (good)	greater than 100	MOhm
Resistance	Winding test conditions	20	C	winding temperature for insulation measurement
Resistance	Windings minimum insulation resistance (in-service)	5	MOhm	1 minute at 500 V test voltage
Resistance	Windings minimum insulation resistance (new)	10	MOhm	1 minute at 500 V test voltage
Speed	Frequency-to-speed gain select	30	RPM/Hz	PCC setting
Speed	Overspeed Trip Level (60 Hz)	2250		PCC threshold
Speed	Secondary Overspeed Trip Speed (60 Hz)	2250		PCC threshold
Speed	Starter Disconnect Speed	400	RPM	InPower setting
Speed	Starter Disconnect Speed (code 5134)	450	RPM	InPower setting
Temperature	High coolant temperature shutdown threshold	230 F / 110	C	shutdown
Temperature	High coolant temperature warning threshold	220 F / 105	C	warning
Temperature	Low coolant temperature warning threshold	70 F (21 C)		4BT3.3 engines
Torque	AVR cover to NDE bracket	5	Nm
Torque	AVR to NDE bracket	5	Nm
Torque	Air cleaner strap clamp	3.4 to 4.5	Nm
Torque	Alternator drive disc bolt and adaptor bolt (section 12.5)	52 +/- 5	Nm
Torque	Alternator drive disc bolts and adaptor bolts	47 to 57	Nm

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	Capacity	Notes
Coolant	50/50 coolant solution (50% pure water and 50% ethylene glycol)
Coolant	50/50 coolant solution (50% water / 50% ethylene glycol)
Engine oil	15W40		7.9 L (8.35 qt)	Refer to the Engine Operator Manual
Fuel	ASTM number 2D fuel	ASTM 2D
Fuel	Number 2 diesel fuel			Direct injection
Grease	Dow Corning silicone heat sink compound type 340 or similar			Apply to base of replacement diode only

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
1	HIGH COOLANT TEMP	Engine has overheated; coolant temperature has risen above shutdown trip point.	Shutdown	Allow engine to cool. Check coolant level, airflow obstructions, fan belt, blower and circulation pumps. Reset and restart.
12	HIGH AC VOLTAGE	One or more phase voltages exceeded 130% of nominal for 0 second, or exceeded high AC voltage threshold for time delay.	Shutdown	Check fault simulation, block load removal, threshold setting, Base board or generator, voltage sense connections.
121	Speed Signal Lost - Shutdown	No engine speed signal detected from crankshaft speed or camshaft position.	Shutdown	Inspect MPU sensor and harness; set MPU tip clearance 0.5-0.6 mm; verify calibration.
13	LOW AC VOLTAGE	One or more phase voltages dropped below low AC voltage threshold for time delay.	Shutdown	Check fault simulation, threshold, overload, output connections, excitation inputs, rotating rectifier diodes, connector or Base board.
1311	Customer Input #1	Configurable customer input 1 fault.	Warning	Check TB1-12; check external wiring; verify fault function settings.
1312	Customer Input #2	Configurable customer input 2 fault.	Warning	Check TB1-14; check external wiring; verify fault function settings.
1317	Low Coolant Level	Optional coolant level sensor indicates low coolant level.	Warning	Add coolant; check coolant level sensor connections and operation; verify calibration.
1318	Low Fuel	Optional low fuel level switch indicates low fuel.	Warning	Add fuel; verify switch operation; check wiring; verify settings.
135	Oil Pressure Sensor OOR - High	Engine oil pressure sensor signal out of range - shorted high.	Warning	Inspect sensor connections; check supply 4.75-5.25 VDC and signal voltage.
135/141	Oil Pressure Sensor OOR - Warning		Warning
14	OVER FREQUENCY	Frequency is 10% above base frequency for approximately 10 seconds.	Shutdown	Check threshold, fuel or air delivery, governor, connector or Base board.
141	Oil Pressure Sensor OOR - Low	Engine oil pressure sensor signal out of range - shorted low.	Warning	Inspect sensor connections; check supply and signal voltage.
1417	Power Down Failure	The PCC has failed to go to sleep.	Warning	Verify calibration; cycle B+ power; replace baseboard if fault persists.
143	Pre-Low Oil Pressure - Warning	Engine oil pressure below low oil pressure warning threshold (40 psig for 5 seconds).	Warning	Check oil level, external leaks, sensor accuracy, oil cooler, regulator, oil pump.
1433	Local E-Stop	State of the Local Emergency Stop has been changed.	Shutdown	Reset local E-Stop; check E-Stop switch and wiring.
1434	Remote E-Stop	State of the Remote Emergency Stop has been changed.	Shutdown	Reset remote E-Stop; install jumper TB1-16 to TB1-15; check switch and wiring.
1435	Low Coolant Temperature	Engine coolant temperature below low coolant temperature warning threshold (70 F / 21 C).	Warning	Verify LCT threshold; check coolant heater operation; check ambient temperature.
1438	Fail to Crank - Shutdown	Engine failed to crank after the generator control received a start signal.	Shutdown	Check battery, starter, starter solenoid, starter relay, CAM/Crank sense.
144	Engine Coolant Temperature OOR Low	Engine coolant temperature signal out of range - shorted low.	Warning	Inspect sensor connections; check sensor resistance; verify calibration.
1442	Weak Battery - Warning	Battery voltage dropped below weak battery voltage threshold (8 V for 2 seconds) while cranking.	Warning	Check battery, connections, charging voltage, DC alternator, harness.
1446	High AC Voltage - Shutdown	One or more phase voltages exceeded high AC voltage threshold (110% of nominal, 10 seconds).	Warning	Check threshold, PCC AVR circuit, generator output connections, PMG, EBS.
1447	Low AC Voltage - Shutdown	One or more phase voltages dropped below low AC voltage threshold (85%, 10 seconds).	Shutdown	Check AVR settings, rotating rectifier diodes, overload, residual magnetism, connections.
1448	Underfrequency	Frequency dropped below underfrequency threshold (6 Hz) for 10 seconds.	Shutdown	Check overrides, threshold, overload, engine governor.
1449	Overfrequency	Frequency went above overfrequency threshold (6 Hz) for 10 seconds.	Shutdown	Verify overfrequency threshold and time delay; check engine governor.
145	Engine Coolant Temperature OOR High	Engine coolant temperature signal out of range - shorted high.	Warning	Inspect sensor connections; check sensor resistance; verify calibration.
146	Pre-High Coolant Temp - Warning	Engine coolant temperature exceeded warning threshold (220 F / 105 C).	Warning	Check ambient temperature, coolant level, cooling components, sensor, thermostat, water pump.
1469	Speed/Hz Mismatch	Perceived engine speed and generator set output frequency do not match.	Shutdown	Check flywheel teeth (110), MPU signal, thresholds (2.0 Hz, 1.5 s), gain (30 RPM/Hz).
1471	High AC Current - Warning	Generator output current exceeded warning limit threshold (110% for 60 seconds).	Warning	Check for short, overload, CTs and CT setup, rating setup, fault override.
1472	High AC Current - Shutdown	Generator output current exceeded shutdown set limit (150% for 10 seconds).	Shutdown	Check for short/overload, CTs and CT setup, rating setup, fault override.
15	UNDER FREQUENCY	Engine speed dropped below 90% of nominal for approximately 10 seconds.	Shutdown	Check fuel supply, intake air supply, load, threshold, governor, connector or Base board.
151	High Coolant Temp - Shutdown	Engine coolant temperature exceeded shutdown threshold (230 F / 110 C).	Shutdown	Check cooling system, coolant level, sensor, thermostat, water pump.
1853	Annunciator Input 1 Fault	Customer fault 1 (input 1, LED 1) on the universal annunciator is active.	Warning	Check condition and wiring at TB1-1; verify configuration; replace annunciator if faulty.
1854	Annunciator Input 2 Fault	Customer fault 2 (input 2, LED 2) on the universal annunciator is active.	Warning	Check condition and wiring at TB1-2; verify configuration; replace annunciator if faulty.
1855	Annunciator Input 3 Fault	Customer fault 3 (input 3, LED 3) on the universal annunciator is active.	Warning	Check condition and wiring at TB1-3; verify configuration; replace annunciator if faulty.
1944	Annunciator Error - Warning	More than one network device configured to activate one annunciator output relay.	Warning	Check network configuration and devices for duplicate use of the same relay output.
2	LOW OIL PRESSURE	Engine oil pressure has dropped below shutdown trip point.	Shutdown	Check oil level, lines and filters; replenish if low; reset and restart; check oil switch.
202	PRE-HIGH COOL TMP	Engine is operating near cooling system capacity.	Warning	Review code 1 correction list.
203	LOW COOLANT TEMP	Engine coolant temperature is 70F (21C) or lower.	Warning	Check coolant heater power, low coolant level, heater element; check current draw.
204,205	CONFIGURABLE INPUT #1,#2	Optional configurable input warning.	Warning	Disconnect signal lead from TB1 and reset control; check CUST_IN1 TB1-14 and CUST_IN2 TB1-12.
212	COOL SENSOR OOR	Coolant temperature sensor output is out of range (high or low).	Warning	Check sender, connectors and wires.
213	LOW BATTERY	Battery voltage supply to control is approaching a low level.	Warning	Check battery charger fuse; recharge or replace battery; clean connections; check wiring/calibration, engine DC alternator, float level.
214	HIGH BATTERY	Battery voltage supply to control is approaching a high level.	Warning	Check float level on battery charger; check battery wiring/calibration.
215	PRE-LOW OIL PRESSURE	Engine oil pressure dropped below warning trip point.	Warning	Follow code 2 procedure.
216	HIGH AC CURRENT	One or more phase currents exceeded high AC warning threshold for time delay.	Warning	Check load and load lead connections.
217	OIL PRESS SENSOR OOR	Engine oil pressure sensor output is out of range (high or low).	Warning	Check sender, connectors and wires.
218	BATTLE SHORT ACTIVE	Control is in Battle Short mode; bypasses several fault shutdowns for emergency operation.	Warning
219	CHARGER FAILURE	Battery charging alternator has not reached acceptable voltage range within selected period (default 120 seconds).	Warning	Refer to engine service manual if fault occurs; check wiring if not failed.
220	FAIL TO SHUTDOWN	Genset continues to run after shutdown command; Battle Short feature enabled.	Warning
221	WEAK BATTERY	During cranking, battery voltage is at or below weak battery warning trip point for time >= weak battery set time.	Warning	See code 213 for corrective action.
222,223,224	ANNUNCIATOR FAULT 1,2,3	Optional configurable annunciator fault.	Warning
225	ANNUNCIATOR OUTPUT CONFIGURATION ERROR	Mismatch in configuration of one of the annunciator relay outputs.	Warning	Check network setup for duplicate use of same annunciator relay output; troubleshoot network devices.
2335	Excitation Fault - Shutdown	Control lost voltage sensing or lost zero cross sensing.	Shutdown	Check configuration, fuse F5 (10 Amp), harness connections, residual magnetism, excitation coil, control board.
234	Overspeed - Shutdown	Engine speed signals indicate engine speed greater than shutdown threshold.	Shutdown	Check MPU sensor and installation; verify overspeed trip level and flywheel teeth (110).
2676	Alternator Frequency Conflict	Alternator line frequency and alternator excitation frequency do not match.	Shutdown	Check alternator line frequency gain; check J22 and J18 connections; check harness and control board.
2677	Fail to Stop - Shutdown	Generator set continues to run after receiving shutdown command from controller.	Shutdown	Check stuck fuel actuator/fuel shutoff valve; check governor module and wiring.
27	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.
2729	IO Module Lost	Intermittent data link between I/O module and PCC (no input fault levels set to Shutdown).	Warning	Check AUX 101 wiring to PCC 1302; verify System IO Board Enable is disabled.
2731	IO Module Lost	Intermittent data link between I/O module and PCC (at least one input fault set to Shutdown).	Shutdown	Check AUX 101 wiring to PCC 1302; verify I/O settings.
2897	Factory Memory Block Corrupt	The control detected a corrupted memory block.	Warning	Connect with InPower 10.0+; select Initial Calibration (Recover Device).
2898	Periodic or Fault Memory Block Corrupt	The control detected a corrupted memory block.	Warning	Connect with InPower 10.0+; select Initial Calibration (Recover Device).
2899	User Memory Block Corrupt	The control detected a corrupted memory block.	Warning	Connect with InPower 10.0+; select Initial Calibration (Recover Device).
2911	Trim Memory Block Corrupt	The control detected a corrupted memory block.	Warning	Connect with InPower 10.0+; select Initial Calibration (Recover Device).
2972	Field Overload	Field AVR Duty Cycle operated at maximum output longer than Max Field Time parameter.	Shutdown	Check voltage sensing into baseboard; check AVR output; check application.
31	OVERSPEED	Engine exceeded normal operating speed; default thresholds 1725 RPM (50 Hz) or 2075 RPM (60 Hz).	Shutdown	Check cold engine, single step large block load removal, fault simulation, threshold, MPU, governor, flywheel teeth, fuel stop settings.
359	Fail to Start - Shutdown	Engine failed to start after expiration of last crank time.	Shutdown	Check flywheel teeth setting (110), starter disconnect speed (400 RPM), fuel supply, glow plugs.
38	FIELD OVERLOAD	Field AVR Duty Cycle has been at maximum for at least 15 seconds.	Shutdown
415	Low Oil Pressure - Shutdown	Engine oil pressure below low oil pressure shutdown threshold (35 psig).	Shutdown	Check oil level, external leaks, sensor accuracy, oil cooler, oil pump.
441	Low Battery Voltage	Battery voltage is low.	Warning	Check battery cables, battery condition, ground connection, DC alternator, charger.
442	High Battery Voltage	Battery voltage above high battery threshold (16 V for 60 seconds).	Warning	Verify charger set to 12 VDC; check fault threshold; check engine DC alternator.
45	SPEED SIGNAL LOST	No magnetic pickup pulses are sensed for Loss of Speed delay; if no MPU, speed sensing is by AC line frequency and fault cannot occur.	Shutdown	Inspect MPU wires/connector pins; test MPU for 3.5 to 15 VAC while cranking; check P11-12 to P11-24; replace Base board if needed.
46	HIGH AC CURRENT	Individual phase alternator output current exceeded high current threshold continuously for more than time delay.	Shutdown	Check load and load lead connections.
5134	Unknown Shutdown	PCC detected that engine RPM decreased to zero while not in run at rated mode.	Shutdown	Check calibration, air intake/exhaust restriction, MPU signal, start disconnect, fuel supply.
61	EMERGENCY STOP	Remote Emergency Stop.	Shutdown	Open (disable) remote emergency stop button; move rocker switch to OFF or press OFF; select desired operating mode.
71	SPEED HZ MATCH	Measured speed and measured AC output frequency do not agree.	Shutdown	Check genset setup for number of flywheel teeth.
72	FAIL TO CRANK	Genset failed to sense rotation for two start attempts; possible control, speed sensing or starting system fault.	Shutdown	Check starter, K7 starter relay, Emergency Stop switch/wiring, MPU circuit or Base board.
73	FAIL TO START	Engine cranks but fails to start; possible fuel system or air induction problem.	Shutdown	Check fuel tank, leaks, plugged fuel lines, fuel filter, air filter; reset and restart; check glow plugs and governor linkage.
74	FAIL TO STOP	Genset continues to run after receiving shutdown command from controller.	Shutdown
75,76	CONFIGURABLE INPUT #1 & #2	Optional configurable input fault.	Shutdown	Disconnect signal lead from TB1 and reset control; check CUST_IN1 TB1-14 and CUST_IN2 TB1-12.
77	SHUTDOWN AFTER BS	A shutdown fault occurred while Battle Short mode was enabled.	Shutdown	Check fault history for faults that may have been bypassed.
81,82,83	ANNUNCIATOR FAULT 1,2,3	Optional configurable annunciator fault.	Shutdown

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

Procedures

Disabling the AMF Feature adjustment

⚠ Must be performed by a qualified technician.

Tools: InPower service tool

Connect to the PCC 1.1 or PCC 2.3 via InPower.
Navigate to Adjustments->Features->Automatic Transfer Switch folder.
Select the Auto Mains Failure Enable parameter.
Double-click on Enabled in the Value field.
Select Disabled from the pop-up choices.
Select Device->Save Adjustments from the top menu bar.
Click Save on the confirmation pop-up.
Disconnect InPower from the PCC1302 after confirmation.

Fuel Injection Pump Speed Lever Adjustment adjustment

Make sure the generator set is off and the battery is disconnected.
If replacing pump or engine, discard speed adjust screw and tamper proof wire and seal.
Replace the low idle screw; reuse throttle screw nut and acorn nut.
Pull throttle lever back and screw new low idle screw until it contacts boss.
Continue tightening until throttle lever is locked in place.
Tighten the throttle lock nut.
Install tamper proof wire and seal.
Set the throttle lever as shown and lock it using seal wire.

Valves - Adjust, All adjustment

Disconnect battery cables
Remove valve cover
Adjust valve lash
Test run unit

Generator/Base Board Isolation Procedure diagnostic

⚠ Hazardous voltage

⚠ Test involves unregulated excitation; disconnect loads

Tools: 12 volt battery, Jumper leads, Voltmeter

Throw line circuit breaker OFF and shutdown set.
Disconnect X and XX exciter stator leads from AC harness.
Prepare to measure output voltage across generator terminals.
Bring two jumpers from 12V battery to X (Field +) and XX (Field -).
Check polarity; correct or test inconclusive.
Start set and connect battery negative to XX.
If rated output voltage or higher and balanced, generator OK; troubleshoot control.
If unbalanced, troubleshoot main stator; if uniformly low, troubleshoot exciter and field.

Testing Diodes diagnostic

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

Tools: Ohmmeter

Disconnect diode pigtails from terminal posts.
Measure resistance between each diode pigtail and its plate.
Reverse meter probes and repeat.
Replace diode if resistance high or low in both directions.

Testing Exciter Rotor diagnostic

Tools: Wheatstone bridge, Ohmmeter

Disconnect six rotor winding leads from rectifier terminal posts.
Measure resistance across each pair of rotor windings U-V, V-W, W-U.
Replace whole rotor shaft assembly if any winding resistance not per Table 6-1.
Measure insulation resistance between winding lead and rotor laminations.
Replace rotor shaft assembly if insulation resistance less than 1 megohm.

Testing Exciter Stator diagnostic

Tools: Wheatstone bridge, Digital ohmmeter, Insulation resistance meter

Measure winding resistance with Wheatstone bridge or digital ohmmeter.
Replace stator if resistance not as specified in Table 6-1.
Disconnect X and XX leads and isolate from ground.
Measure resistance between either lead and stator laminations.
Replace stator if insulation resistance less than 1 megohm.

Testing Main Rotor diagnostic

Tools: Wheatstone bridge, Digital ohmmeter, Torque wrench

Disconnect two main rotor leads from rotating rectifier terminals.
Measure resistance between two leads with Wheatstone bridge or digital ohmmeter.
Replace rotor if resistance not as specified in Table 6-1.
Measure resistance between either lead and main rotor laminations.
Replace rotor if insulation resistance less than 1 megohm.
Torque terminals to 24 in-lbs (2.7 Nm) when reassembling.

Testing Main Stator diagnostic

Tools: Wheatstone bridge, Insulation tester

Measure resistance across each pair of stator leads U1-U2, U5-U6, V1-V2, V5-V6, W1-W2, W5-W6.
Use Wheatstone bridge or ohmmeter with at least 0.001 ohm precision.
Replace stator if any winding resistance not as specified in Table 6-1.
Disconnect AVR completely before insulation test.
Disconnect Neutral to Earth and any connections.
Use 500 or 1000 V insulation tester for low voltage generators up to 690V.
Minimum insulation value is 1.0 Meg-Ohm to Earth; dry windings if below.

AC Load Connections (Circuit Breaker) installation

⚠ Improper installation can lead to electrocution and property damage.

Tools: Insulated wrench, Torque wrench

Shut down and disable the generator set (Off then E-Stop, cool down).
Turn off battery charger AC and disconnect negative battery cable.
Remove enclosure side panel to access main circuit breaker box.
Place circuit breaker handle in OFF position.
Remove four bolts holding circuit breaker cover.
Connect conductors to load-side terminals, neutral lug, and grounding lug.
Torque circuit breaker terminals per breaker label.
Torque neutral lug to 31.1 Nm (275 in-lb).
Torque equipment grounding lug to 13.8 Nm (120 in-lb).
Fill stub-up openings with duct seal or mastic tape.
Install circuit breaker cover.

Connect Battery installation

⚠ Do not connect battery cables until installation is complete to prevent accidental startup.

Connect the positive battery terminal.
Connect the negative battery terminal.
Make sure black and red battery cable boots are in place.

Connecting the Battery installation

⚠ Accidental or remote starting of the generator set can cause severe personal injury or death.

Press the generator set's O (Off) button and allow it to cool.
Turn off and disconnect the battery charger from the AC source before disconnecting battery cables.
Disconnect the negative (-) cable from the battery.
Connect the positive battery terminal.
Connect the negative battery terminal.
Make sure black and red battery cable boots are in place.

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
above 300 volts L-L		X1 & X2	CT secondaries	CTs have dual secondaries (3 pins marked X1, X2 & X3).
below 300 volts L-L		X1 & X3	CT secondaries	CTs have dual secondaries (3 pins marked X1, X2 & X3).

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 4BT3.3 family

Part #	Description	Category
0140-3765	Air Cleaner Element	air_filter
0140-3829	Air Cleaner Kit (Normal Duty) (cw Clamp)	air_filter
0140-3830	Air Cleaner (Normal Duty) (cw Clamp)	air_filter
0140-3840	Air Cleaner Element	air_filter
0179-3782	Air Cleaner Instl	air_filter
0541-1111	Air Cleaner Kit (Heavy Duty)	air_filter
0524-0826	Sealant-Thread 577 (250ml)	fluid
0149-2744	Separator-Fuel/Water	fuel_filter
0155-4285	Gasket-Exhaust	gasket
0155-4286	Gasket-Exhaust	gasket
0130-6174	Hose-Radiator-Top (Denso radiator)	hose
0130-6175	Hose-Radiator-Bottom (Denso radiator)	hose
0501-0874	Line-Fuel (Return)	hose
0501-0875	Line-Fuel (Feed)	hose
0501-0955	Line - Fuel (3/8" x 740mm)	hose
0501-0956	Line-Fuel (3/16" x 850mm)	hose
0502-1507	Adapter-Hose (Oil)	hose
0503-0685	Clamp-Hose (6mm-16mm)	hose
0503-1620	Hose-Fuel (3/8" ID X 5/8" OD)	hose
0503-2474-06	Hose-Steam	hose
0503-2474-07	Hose-Steam	hose
0503-2546	Hose-Flexible (air cleaner)	hose
0503-2633-01	Hose-Drain	hose
0503-2653	Hose-Coolant (Top)	hose
0503-2654	Hose-Coolant (Bottom)	hose
M-1675	IGNITION COIL	ignition_coil
FS-1406-2	THROTTLE SHAFT AND LEVER	oil_filter
FS-1440-3	CARBURETOR ASSEMBLY	oil_filter
M-13964	FRONT PULL GOVERNOR ASSEMBLY	oil_filter
0100-3922	Engine-B3.3G1	other_service
0100-3985	Engine-Accessories	other_service
0130-6147	Cooling Fan (Denso radiator)	other_service
0130-6149	Radiator-B3.3 (also listed as Radiator-SRF)	other_service
0130-6406	Radiator Cap (Denso)	other_service
0130-6598	Radiator-SRF	other_service
0130-6600	Radiator Cap	other_service
0155-4215	Guard-Exhaust (Support)	other_service
0155-4311-02	Guard-Exhaust	other_service
0159-1552	Cap-Filler (fuel tank)	other_service
0179-3786	Heater Instl	other_service
0179-3998	Muffler Instl - Enclosure	other_service
0179-4468	Battery Charger Instl	other_service
0179-4489	Radiator Instl	other_service
0179-4498	Genset Instl (SRF Radiator)	other_service
0179-4636	Skid Assy (With Tank)	other_service
0179-4900	Circuit Breaker Instl (MCCB)	other_service
0179-4915	Circuit Breaker Instl (MCB)	other_service
0300-6031	Control Assy	other_service
0320-1981-01	Accessories-CB (SD Contact)	other_service
0320-1981-02	Accessories-CB (Shunt Trip)	other_service
0320-2225-01	Accessories-CB (Shunt Trip)	other_service
0320-2225-02	Accessories-CB (SD Contact)	other_service
0331-0618-02	Locknut Conduit	other_service
0332-4001-01	Rail-Terminal Block (300mm)	other_service
0333-0690	Heater-Engine Coolant-240v.	other_service
0333-0699	Heater-Engine Coolant-120v.	other_service
0337-3583-03	Strap-Ground	other_service
0337-3583-04	Strap-Ground	other_service
0338-4487	Harness-Engine (Mechanical governor)	other_service
0338-4646	Harness-Engine	other_service
0338-4720	Harness-Engine (Electronic governor)	other_service
0338-4819-02	Harness AC	other_service
0338-4819-03	Harness AC	other_service
0405-9086	Enclosure Assy	other_service
0416-1242	Battery	other_service
0504-0264-01	Valve-Hydraulic (Oil)	other_service
0504-0267	Valve-Ball M22 lock	other_service
0504-0284	Valve-Drain (1/2"BSP)	other_service
0505-0019	Bushing-Reducer	other_service
0505-2235	Adaptor-Pipe	other_service
0526-0399-56	Washer-Flat (M5)	other_service
0526-0399-60	Washer-Flat (M8)	other_service
0526-0399-62	Washer-Flat (M10)	other_service
0541-1161	Muffler - Loose (Option)	other_service
0800-0309-93	Screw-Hex Head (M5)	other_service
0800-3017-19	Screw-Hex Head (M8 X 20)	other_service
0800-3017-35	Screw HHC (M10)	other_service
0800-3017-37	Screw-Hex Head (M10 X 25)	other_service
0850-0114-52	Washer-Lock (M5)	other_service
0850-0114-54	Washer-Lock (M8)	other_service
0850-0114-55	Washer-Lock (M10)	other_service
0862-0026-55	Nut-Hex (M8)	other_service
0862-0026-56	Nut Hex (M10)	other_service
0872-0020-01	Standoff	other_service
0872-0021	Standoff	other_service
961-0518	(Issue1)	other_service
A048W006	Cummins lifting kit	other_service
M-1686	STARTING SYSTEM	other_service
0120-1346	Pump-Oil	pump
0150-2651	Speed Sensor-Mag (electronic governor)	sensor
0193-0430-01	Sender-Pressure	sensor
0193-0562	Gauge-Fuel Level	sensor
0193-0567	Gauge-Fuel Level	sensor
0193-0568	Coolant Level Switch / Sensor-Low Coolant Level	sensor
0309-0436	Sender-Temperature (E2, E4) (listed as Thermostat in the SRF radiator section)	sensor
0309-0641-19	Sender-Pressure (also listed as Switch-Pressure)	sensor
0309-0707-04	Switch-Level (Fuel)	sensor
0193-0432	Thermostat	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 4BT3.3?

The Cummins/Onan 4BT3.3 engine has an oil capacity of 7.9 liters.

What is the displacement of the Cummins/Onan 4BT3.3?

The Cummins/Onan 4BT3.3 has a displacement of 3.3 liters with 4 cylinders.

Which generators use the Cummins/Onan 4BT3.3 engine?

The Cummins/Onan 4BT3.3 powers 7 generator set(s), including Cummins/Onan C25 D6, Cummins/Onan C30 D6, Cummins/Onan C35 D6, Cummins/Onan C40 D6, Cummins/Onan C50 D6.

How often should you change the oil in the Cummins/Onan 4BT3.3?

The Cummins/Onan 4BT3.3 oil change interval is every 200 hours.

What is a common problem with the Cummins/Onan 4BT3.3 engine?

A commonly reported issue on generators using the Cummins/Onan 4BT3.3 is: Weakness and Sleepiness. Fix: IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired..