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Jeep XJ Trouble Codes

How to read XJ Computer Diagnostic Codes

Switch the ignition key on-off-on-off-on.  (Do not go all the way to START!)
The "check engine" light will flash. Count the flashes.
Each code is a two digit code, so a (for example) 23 would be:


It will never flash more than 9 times, watch for pauses!

55 is end of codes, 33 is normal if you dont have air conditioning.

Please note that some codes are NOT included below, this
is not a complete listing, but it IS very close to complete.

88 Start of test (This only appears on DRBII, it's not blinked out)

11 No ignition reference signal detected during cranking (bad hall


OR timing belt skipped one or more teeth; or intermittent

loss of either camshaft or crankshaft position sensor

12 Memory Standby power lost (battery cable disconnected)

13* No change in MAP from start to run

14* MAP sensor circuit open or shorted; voltage too low

15 No speed/distance sensor signal

16* Loss of battery voltage detected with engine running

17 Engine stays cold too long (bad thermostat)

21 Oxygen sensor signal out of range, possibly shorted

22* Coolant sensor signal out of range (or disconnected to set timing)

23 Intake air temperature signal out of range

24* Throttle position circuit out of range

25 Automatic Idle Speed (AIS) motor driver circuit shorted

or target idle not reached, vacuum leak found

26 Peak injector circuit voltage has not been reached

27 Logic module fuel circuit internal problem


27 TBI injector does not respond properly to control signal

31 Evaporator Purge solenoid circuit open or shorted OR

Evaparator solenoid circuit

32 EGR system failure OR

Power loss lamp open or shorted

33 Air conditioning clutch relay circuit open or shorted

34 Speed control vacuum or vent solenoid circuits open or shorted

35 Cooling fan relay circuit open or shorted

36 Wastegate control circuit open or shorted

37 Shift indicator light failure, 5-speed (blown bulb) OR

Park/neutral switch failure


37 Torque converter unlock circuit open or shorted, A-413 4-speed auto

41* Alternator field control circuit open or shorted

42 Automatic shutdown relay circuit open or shorted

42 Fuel pump relay control circuit

42 Fuel level unit - no change over miles


42 Z1 voltage missing when autoshutdown circuit energized (whatever that means)

43 Peak primary coil current not achieved with max dwell time


43 Cylinder misfire

43 Problem in power module to logic module interface

44 No FJ2 voltage present at logic board


44 Logic module self-diagnostics indicate problem


44 Battery temperature out of range (see Note #1!)

45 Turbo boost limit exceeded (engine was shut down by logic module)

46* Battery voltage too high during charging or charging system

voltage too low

47 Battery voltage too low and alternator output too low

51 Oxygen sensor stuck at lean position


51 Internal logic module fault ('84 turbo only)

52 Oxygen sensor stuck at rich position


52 Internal logic module fault ('84 turbo only)

53 Logic module internal problem

54 No sync pickup signal during engine rotation (turbo only)


54 Internal logic module fault ('84 turbo only)

55 End of codes

61 "Baro" sensor open or shorted

62 EMR mileage cannot be stored in EEPROM

62 PCM failure SRI mile not stored

63 Controller cannot write to EEPROM

64 Catalytic converter efficiency failure

65 Power steering switch failure

* Activates Power Limited/Check Engine light.

These codes cover multiple years and engines (2.2l, 2.5l, 3.0l).

NOTE #1. The power module has an air-cooled resistor which is

used to sense the incoming air temperature. This information is fed

to the logic module and is used to control the duty cycle of the

field current in the alternator. This code applies ONLY to

alternators whose voltage is computer regulated. The battery voltage

is sensed by the logic module -- there is an internal takeoff from

the wire feeding the NVRAM keep-alive power circuit which is fed to

a voltage comparator. So...if you lose the feed to keep RAM

information stored when the engine's off, you also lose battery voltage


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