1991-1995 Jeep Wrangler (YJ) Trouble Codes

The diagnostic trouble codes on all models can be extracted from the
Powertrain Control Module (PCM) using a SCAN tool. On 1991 through 1995
models only, the PCM can be placed in the diagnostic mode and the
trouble codes flashed on the Check Engine light.The PCM will
illuminate the CHECK ENGINE light on the dash if it recognizes a fault
in the system. The light will remain lit until the problem is repaired
and the code cleared or the PCM does not detect any malfunction for
several consecutive drive cycles.To extract the diagnostic trouble codes, perform the following steps:Without
starting the engine, turn the ignition key ON, OFF, ON, OFF and ON. The
CHECK ENGINE light on the dash will begin to flash.If any
trouble codes are stored in the PCM memory, the CHECK ENGINE light will
flash the number of the first digit, pause and flash the number of the
second digit. For example, Code 23, air temperature sensor circuit
would be indicated by two flashes, pause three flashes. A long pause
will appear between individual codes if more than one code is present.
Carefully observe the flashes and record the exact code number(s) onto
paper.After the stored codes have been indicated (or if
everything in the self diagnosis system is functioning properly), the
CHECK ENGINE light will flash a Code 55.If the ignition key is
turned OFF during the code extraction process and possibly turned back
ON, the self diagnostic system will automatically invalidate the
procedure and must be restarted.Code Probable Cause11* Ignition12* Direct battery input to PCM was disconnected within
the last 50 key-on cycles.13** Manifold Absolute Pressure (MAP) Sensor Vacuum14** Manifold Absolute Pressure (MAP) Sensor Electrical15** Distance sensor or circuit17* Engine running too cool21** Oxygen sensor or circuit22** Coolant temperature sensor or circuit23** MAT sensor or circuit24** Throttle Position Sensor (TPS) sensor or circuit25** Automatic Idle Speed (AIS) circuit27* Fuel injector control31* EVAP solenoid or circuit33* Air conditioning clutch relay41* Alternator field42* Automatic shutdown relay44* Battery temperature sensor46** Battery over voltage47** Battery under voltage51** Oxygen sensor - lean condition52** Oxygen sensor - rich condition53* Internal engine controller fault54* Distributor sync pickup55* End of Code output62* Emissions Maintenance Reminder (EMR) mileage accumulator63* Controller failure EEPROM write denied
* - Check engine lamp will not illuminate at all times if this code was
recorded. Cycle ignition key as described and observe code flashed by
check engine lamp.



** - Check engine lamp will illuminate during engine operation if this
code was recorded.If you find this guide helpful and / or informative please click "Yes" below. reds_renders - Veteran of:Operation Desert Shield / Desert StormOperation Restore Hope / United Nations Operations in Somalia IIOperation Enduring FreedomOperation Iraqi Freedom III