CUMMINS ISB ENGINE FAULT CODES

You are driving down the highway and all of a sudden, your "Check Engine" Light comes on - or worse, your "Stop Engine" light comes on.   What to do? Well, before you call Freightliner or Cummins, did you know that you can access the engine error code that caused the light to come on? This could be very helpful to have BEFORE you call for help.   Here is how you do it...

First, look under the dash where you will find two switches.   One switch is to increase/decrease engine idle speed and the other is the Check Engine Diagnostic switch.   Now, turn the ignition switch to run - DON"T START - and press the engine diagnostic switch and hold it.   Now the CHECK ENG and STOP ENG lights will flash the error code and you can determine what the code is from the table below.   Example the amber CHECK ENG light will flash once the red STOP ENG light will flash out the error code.   For error code 123, the CHECK ENG light will flash once, followed by the STOP ENG light flashing as follows -- FLASH pause FLASH FLASH pause FLASH FLASH FLASH -- then the CHECK ENG light will flash once and the cycle will repeat.   If you have more than one error code press the IDLE INCREASE switch to go to the next error code.   ALL Inactive codes will not display.   If you any inactive codes, you will need the INSITE computer to reset them All inactive codes will only show a solidly lit CHECK ENG and STOP ENG light.

Fault Code

Reason

Effect (only when engine fault code is active)

111 Yellow

ECM Internal hardware error

Possible no effect or engine may run rough or not start

115 Yellow

No engine speed or position signal detected at pin 17 of the engine harness

Engine power derate.   Possible white smoke.

122 Yellow

High voltage detected at the boost pressure sensor signal pin 45 of the engine harness.

Engine could derate to no-boost fueling.

123 Yellow

Low voltage detected at the boost pressure sensor signal pin 45 of the engine harness.

Engine could derate to no-boost fueling.

124 Yellow

Intake manifold pressure signal indicates boost pressure has exceeded the maximum limit for the given engine rating

Engine could derate to no-boost fueling.

131 Yellow

High voltage detected at throttle position signal pin 30 of the OEM harness.

Engine idles when idle validation switch indicates idle and ramps up to a default set speed when the idle validation switch indicates off-idle.

132 Yellow

Low voltage detected at throttle position signal pin 30 of the OEM engine harness.

Engine idles when idle validation switch indicates idle and ramps up to a default set speed when the idle validation switch indicates off-idle.

135 Yellow

High voltage detected at oil pressure signal pin 33 of the engine harness.

Default value used for oil pressure.   No engine protection for oil pressure.

141 Yellow

Low voltage detected at oil pressure signal pin 33 of the engine harness.

Default value used for oil pressure.   No engine protection for oil pressure.

143 Yellow

Oil pressure signal indicates oil pressure below the low engine protection limit.

Power derate and possible engine shutdown if engine protection feature enabled.

144 Yellow

High voltage detected at coolant temperature signal pin 23 of the engine harness.

Default value used for coolant temperature.   No engine protection for coolant temperature.

145 Yellow

Low voltage detected at coolant temperature signal pin 23 of the engine harness.

Default value used for coolant temperature.   No engine protection for coolant temperature.

146 Yellow

Coolant temperature signal indicates coolant temperature has exceeded the engine protection limit.

Power derate and possible engine shutdown if engine protection feature enabled.

151 Red

Coolant temperature signal indicates coolant temperature has exceeded the engine protection limit.

Speed derate and possible engine shutdown if engine protection shutdown feature is enabled.

153 Yellow

High voltage detected at intake manifold temperature signal pin 34 of the engine harness.

Default value used for intake manifold temperature.   No engine protection for intake manifold temperature.

154 Yellow

Low voltage detected at intake manifold temperature signal pin 34 of the engine harness.

Default value used for intake manifold temperature.   No engine protection for intake manifold temperature.

155 Red

Intake manifold air temperature signal indicates intake manifold air temperature is above the engine protection limit.

Speed derate and possible engine shutdown if engine protection shutdown feature is enabled.

191 None

Error detected in auxiliary control circuit 1 at pin 21 of the engine harness.

Auxiliary device or clutch controlled by this circuit will not function properly.

234 Red

Engine speed signal indicates engine speed has exceeded the overspeed limit.

Fuel to injectors disabled until engine speed falls below the overspeed limit.

235 Maint.

Coolant level signal at pin 37 of the engine harness indicates coolant level is low.

Power and/or speed derate and possible engine shutdown if engine protection shutdown feature is enabled.

241 Yellow

Vehicle speed signal on pins 8 and 18 of the OEM harness has been lost.

Engine speed limited to "Max Engine speed without VSS".   Cruise control, gear-down protection and the road speed govenor will not work.   Trip information data that is based on mileage will be incorrect.

242 Yellow

Tampering has been detected on the vehicle speed circuit pins 8 and 18 of the OEM harness.

Engine speed limited to "Max Engine speed without VSS".   Cruise control, gear-down protection and the road speed govenor will not work.   Trip information data that is based on mileage will be incorrect.

243 None

Error detected in the exhaust brake control circuit at pin 42 of the engine harness.

Exhaust brake of the engine brake will not operate.

245 None

Error detected in the fan clutch control circuit at pin 31 of the engine harness.

Fan clutch will not function properly.

261 Yellow

Fuel temperature signal indicates fuel temperature has exceeded the engine protection and/or pump protection limit.

Power derate.

264 Yellow

High or low voltage detected at the fuel temperature sensor signal circuit inside the VP44 pump controller.

Default value used for fuel temperature.   Possible low power and no engine protection for fuel temperature.

278 Yellow

Error detected in lift pump circuit at pin 11 of the engine harness.

Possible low power, engine may die, run rough or be difficult to start.

283 Yellow

High voltage detected at main engine speed/position sensor voltage supply pin 8 of the engine harness.

ECM will use the VP44 pump speed signal as a backup.   Possible white smoke.

284 Yellow

Low voltage detected at main engine speed/position sensor voltage supply pin 8 of the engine harness.

ECM will use the VP44 pump speed signal as a backup.   Possible white smoke.

352 Yellow

Low voltage detected at engine position sensor +5 volt supply, pin 10 of the engine harness.

Default value used for sensors connected to this +5 VDC supply.   Engine will derate to non-boost fueling and loss of engine protection for oil pressure, intake manifold pressure and coolant temperature.

361 Red

Continuous power detected at VP44 fuel control valve.

Fueling to injectors disabled.   Engine dies.

362 Yellow

Low voltage or no voltage detected at the VP44 fuel control valve.

Engine wil die....OR....run rough.

363 Yellow

No fuel control valve movement detected by the VP44 pump controller.

Engine power derate.   Engine possibly dies.

364 Yellow

No communications or invalid data transfer rate detected on data link between ECM and VP44 pump controller at pins 4 and 13 of the engine harness...OR...no voltage detected at pin 7 of the VP44 fuel pump controller.

Engine will run at a backup mode set speed when throttle is off-idle....or engine will not start.

365 Yellow

Low voltage detected at the VP44 pump controller supply voltage circuit.

Possible engine dying....or running rough.

366 Yellow

VP44 pump controller battery voltage measurement is outside the range between 6 and 24 VDC.

Possible no effect.   Engine may run rough or die if pump supply voltage is below 6 VDC.

367 Red

VP44 pump speed/position sensor signal lost.

Fueling to injectors disabled.   Engine dies.

368 Yellow

The VP44 pump cannot achieve the timing value being commanded by the ECM.

Engine power derate.

372 Yellow

VP44 pump controller detects continuous voltage at idle select pin 16 of the engine harness...OR...pump controller detects an open circuit or short circuit to ground at idle select pin 16 of the engine harness.

If communications is lost between the ECM and VP44 pump controller, engine will either only idle...OR...will be stuck at a slightly higher idle speed.

373 Red

High voltage detected at VP44 shut off signal pin 6 of the engine harness.

Fueling to injectors disabled.   Engine dies.

374 Yellow

VP44 pump controller has detected an internal error

Engine power derate....OR...engine dies.

375 Yellow

Engine ECM is requesting a fueling or timing value that the VP44 pump cannot achieve.

Possible no effect...OR...engine will run at back-up set speed when the accelerator is off-idle.

376 Red

No calibration in the VP44 pump controller.

Fueling to injectors disabled.   Engine will die.

377 Yellow

VP44 pump controller is not powering down when key switch power is removed from the ECM.

Equipment batteries may be drained low during long shutdown periods.

381 Yellow

Error detected in cold-start aid relay 1 enable circuit at pin 41 of the OEM harness.

Intake air heater cannot be fully energized by the ECM.   Possible white smoke and/or hard starting.

382 Yellow

Error detected in cold-start aid relay 2 enable circuit at pin 31 of the OEM harness.

Intake air heater cannot be fully energized by the ECM.   Possible white smoke and/or hard starting.

384 None

Error detected in auxiliary control circuit 2.

Auxiliary device or clutch controlled by this circuit will not function properly.

385 Yellow

High voltage detected at OEM harness sensor +5 VDC supply pin 10 of the OEM harness.

Sensors connected to this +5 VDC supply will not function.

386 Yellow

High voltage detected at the engine position sensor +5 VDC supply pin 10 of the engine harness.

Default value used for sensors connected to this +5 VDC supply.   Engine will derate to no-boost fueling and loss of engine protection for oil pressure, intake manifold temperature, and coolant temperature.

387 Yellow

High voltage detected at the throttle position sensor +5 VDC supply pin 29 of the OEM harness.

Engine idles when idle validation switch indicates idle and ramps up to a default value set speed when idle validation switch indicates off-idle.

391 Yellow

Error detected in VP44 power supply relay enable circuit at pin 43 of the engine harness.

Possible no effect on performance or engine may die.

415 Red

Oil pressure signal indicates oil pressure below the very low engine protection limit.

Speed derate and possible engine shutdown if engine protection shutdown feature is enabled.

418 WIF

Water-in-fuel signal indicates the water in the fuel filter needs to be drained.

Excessive water in the fuel can lead to severe fuel system damage.

422 Yellow

Voltage detected simultaneously on both the coolant level high and low signal pins 27 and 37 of the engine harnes...OR...no voltage detected on either pin.

No engine protection for coolant level.

429 Yellow

Low voltage detected at water-in-fuel signal pin 40 of the OEM harness.

No water-in-fuel protection.

431 Yellow

Idle validation signals on pins 25 and 26 of the OEM harness indicates no voltage detected simultaneously.

No effect on performance, but loss of idle validation.

432 Yellow

Idle validation signal at pin 26 of the OEM harness indicates the throttle is at the idle position when the throttle position signal at pin 30 of the OEM harness indicates the throttle is not at the idle position...OR...idle validation signal at pin 26 of the OEM harness indicates the throttle is not at the idle position when the throttle position signal at pin 30 of the OEM harnes indicates the throttle is at the idle position.

Engine will only idle.

433 Yellow

Boost pressure signal indicates boost pressure is high when other engine parameters (i.e.  speed and load) indicate boost pressure should be low...OR...boost pressure is low when other engine parameters indicates it should be high.

Engine will derate to no-boost fueling.

434 Yellow

All data gathered by the ECM since the last key on (i.e.  faults, trip information data, etc) was not stored to permanent memory at the last key off.

None on performance.   Fault code table, trip information data, and maintenance monitor data may be inaccurate.

441 Yellow

Voltage detected at OEM power supply pin 38, 39 and 40 of the engine harness indicates the ECM supply voltage fell below 6 volts.

Engine will die...OR...run rough.

442 Yellow

Voltage detected at ECM power supply pin 38, 39 and 40 of the engine harness indicates the ECM supply voltage is above the maximum system voltage level.

None on performance.

443 Yellow

Low voltage detected at throttle position sensor +5 VDC supply pin 29 of the OEM harness.

Engine idles when idle validation switch indicates idle and ramps up to a default set speed when idle validation switch indicates off-idle.

444 Yellow

Low voltage detected at OEM harness sensor +5 VDC supply pin 10 of the OEM harness.

Sensors connected to the +5 VDC supply (i.e.  remote throttle position sensor) will not function.

488 Yellow

Intake manifold air temperature signal indicates intake manifold air temperature is above the engine protection limit.

Power derate and possible engine shutdown if engine protection shutdown feature is enabled.

515 Yellow

High voltage detected at the auxiliary +5 VDC sensor supply voltage pin 49 of the engine harness.

Auxiliary device will not function.

516 Yellow

Low voltage detected at the auxiliary +5 VDC sensor supply voltage pin 49 of the engine harness.

Auxiliary device will not function.

556 Yellow

Idle validation signals on pin 25 and 26 of the OEM harness indicates voltage detected simultaneously on both pins.

Engine will not idle.

- Thanks to G-Man for the above info!