The check engine light on most Chryslers can be retrieved by simply turning the key on and off three times. Turn the key to run position, back one click, run, back one click, run, the check engine light should start to flash on older Jeeps. One flash, pause two flashes, would be code 12. It should start with code 12 ends with code 55. It will repeat the codes three times before moving to the next code. OBDII vehicles (anything 96-up) use codes that contain both letters and numbers. Newer Jeeps with the digital odometers will actually display codes on the odometer. For example, it may display P0301, which would be a misfire on cylinder one. Almost all parts stores will scan OBDII vehicles for free, if you take it to a parts store write down the actual code number for your reference. Once you have some sort of code number, we can usually get you straighten around, and answer any questions you may have.
Easiest way to use this list, is to hit Ctrl-F in your browser and type in the code number you are looking for and let the computer find it for you.
11 No crank reference signal detected during engine cranking.
12 Direct battery input to PCM was disconnected within the last 50 key-on cycles.
13 No difference recognized between the engine MAP reading and the barometric (atmosphereic) pressure reading at start-up
14 MAP sensor input below minimum or above acceptable voltage.
15 No vehicle distance (speed) sensor signal detected during road load conditions.
17 Engine coolant temperature remains below normal operating temperatures during vehicle travel (thermostat).
21 Neither rich nor lean condition detected from the oxygen sensor input.
22 Engine coolant temperature sensor input above maximum or below minimum acceptable voltage.
23 Intake manifold air temperature sensor input above maximum or below minimum acceptable voltage.
24 Throttle position sensor input above maximum or below minimum acceptable voltage.
25 A shorted condition detected in one or more of the idle air control motor circuits.
27 Injector output driver does not respond properly to the control signal.
33 An open or shorted condition detected in the A/C clutch relay circuit.
34 An open or shorted condition detected in the speed control vacuum or vent solenoid circuits.
35 An open or shorted condition detected in the radiator fan relay circuit.
41 An open or shorted condition detected in the generator field control circuit.
42 An open or shorted condition detected in the auto shutdown relay circuit.
44 An open or shorted condition exists in the engine coolant temperature sensor circuit or a problem exists in the PCM's battery temperature voltage circuit.
46 Battery voltage sense input above target charging voltage during engine operation.
47 Battery voltage sense input below target charging voltage during engine operation.
51 Oxygen sensor signal input indicates lean air/fuel ratio condition during engine operation.
52 Oxygen sensor signal input indicates rich air/fuel ratio condition during engine operation.
53 PCM internal fault condition detected.
54 No fuel sync (camshaft signal) detected during engine cranking.
55 Completion of diagnostic trouble code display on the malfunction indicator lamp (check engine lamp).
62 Unsuccessful attempt to update SRI (service reminder indicator) miles in the PCM EEPROM.
63 Unsuccessful attempt to write to an EEPROM location by the PCM.