Check Engine Light: YJ, TJ and JK Models
The check engine light comes on when there is any electrical, mechanical, or sensor fault. If you turn the ignition key on and off 5 times, you will see the error codes flashing on the instrument cluster.
Below is an example from a JK (2007 to present):
P0306: Cylinder 6 is Misfiring
To help you understand the problems that your car may be experiencing, we have listed a few of the common codes that come up with Jeep Wranglers. This will help in a self diagnosis.
These codes will be P-code suffixes (meaning the code will be, for example: P1234):
P0107: MAP sensor input below minimum acceptable voltage.
P0108: High MAP sensor input above maximum acceptable voltage.
P0112: Low Intake air (charge) temperature sensor input below the minimum acceptable
P0113: High Intake air (charge) temperature sensor input above the maximum acceptable
P0116: Coolant Temperature Sensor Performance error has been detected in the coolant
P0117: Engine coolant temperature sensor input below the minimum acceptable voltage.
P0118: Engine coolant temperature sensor input above the maximum acceptable voltage.
P0121: Throttle Positioning Sensor signal does not correlate to MAP sensor signal.
P0158: Heated Oxygen Sensor (HO2S). Wiring short within the sensor or damaged sensor
A diagnosis tool, such as the one pictured, can be invaluable to a team of mechanics. Not all mechanical fixes can be self diagnosed by sound, feeling, or even sight. These tools plug into your ECU plug located under the steering wheel. At times your car may have a few electrical faults that cannot be felt or recognised until such an item is plugged into your car’s computer.
Now you’ve read this, try it out and tell us if our tips helped you. You never know, maybe there’s an electrical or mechanical fault in your car that you haven’t even found yet!