TJ Computer Codes


Staff member
Jeep Wrangler TJs have the ability to display error codes on the odometer. If your check engine light comes on, just follow this procedure:

Key off, push and hold the trip reset button.
Turn key to run (not start) and back to off again.
Release trip reset button.

Trouble code should display in the odometer window. If the gauges run through a test run and the odometer cycles through all numbers like 999999, you released the trip reset button too early.
Last edited:

11 |No ignition reference signal detected during cranking (bad Hall effect) OR timing belt skipped one or more teeth; OR loss of either camshaft or crankshaft position sensor. Can cause the engine to stop working entirely with no limp-home mode.
12 |Battery or computer recently disconnected 13 MAP sensor or vacuum line may not be working 14 MAP sensor voltage below .16V or over 4.96V 15 No speed/distance sensor signal 16 Loss of battery voltage detected with engine running 17 Engine stays cool too long (bad thermostat or coolant sensor?) 21 Oxygen sensor signal doesn't change (stays at 4.3-4.5V). Probably bad oxygen sensor 22 Coolant sensor signal out of range - May have been disconnected to set timing
23 |Incoming air temperature sensor may be bad 24 Throttle position sensor over 4.96V 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 (need to check computer signals, voltage reg, injectors) 27 Injector circuit isn't switching when it's told to (TBI) OR (MPI) injector circuit #1 not switching rightOR (turbo) injector circuit #2 not switching rightOR (all 1990-) injector output driver not responding- check computer, connections
31 |Bad evaporator purge solenoid circuit or driver 32 (1984 only) power loss/limited lamp or circuit 32 EGR gases not working (1989 - check vacuum, valve 32 (1990-92, all but Turbo) computer didn't see change in air/'fuel ratio when EGR activated - check valve, vacuum lines, and EGR electrical 33 Air conditioning clutch relay circuit open or shorted (may be in the wide-open-throttle cutoff circuit) 34 (1984-86) EGR solenoid circuit shorted or open 34 (1987-1991) speed control shorted or open 35 Cooling fan relay circuit open or shorted 35 (trucks) idle switch motor fault - check connections 36 (turbo) Wastegate control circuit open or shorted 36 (3.9/5.2 RWD) solenoid coil circuit (air switching) 36 (Turbo IV) #3 Vent Solenoid open/short 37 Shift indicator light failure, 5-speed OR part throttle lock/unlock solenoid driver circuit (87-89) OR solenoid coil circuit (85-89 Turbo I-IV) OR Trans temperature sensor voltage low (1995 and on)
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 OR Z1 voltage missing when autoshutdown circuit energized 43 Peak primary coil current not achieved with max dwell time OR 43 Cylinder misfire OR Problem in power module to logic module interface 44 No FJ2 voltage present at logic board OR Logic module self-diagnostics indicate problem OR Battery temperature out of range
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 (Bob wrote: may be tripped by a bad EGR system causing a rich condition, and the O2 sensor trying to compensate. The O2 sensor may still be good. The EGR assembly consists of two pieces, the valve and the vacuum transducer (round plastic unit with cylinder on top and both electrical and vacuum connections) OR Internal logic module fault ('84 turbo only).
52 |Oxygen sensor stuck at rich position OR Internal logic module fault ('84 turbo only) 53 |Logic module internal problem 54 No sync pickup signal during engine rotation (turbo only) OR Internal logic module fault ('84 turbo only) - or camshaft sensor/distributor timing (7) 55 End of codes 61 "Baro" sensor open or shorted 62 EMR mileage cannot be stored in EEPROM OR PCM failure SRI mile not stored
63 |Controller cannot write to EEPROM 64 Catalytic converter efficiency failure 65 Power steering switch failure 88 Start of test (not usually given, don't expect it)