Your check engine light, as soon as it turns on, is your Jeep"s means of letting you know that that is on-board diagnostic system has detected a problem. Because the irradiate doesn"t offer you lot information, the only means of identify why the light is top top is to operation a straightforward diagnostic check.

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This article uses to the Jeep grand Cherokee WJ (1999-2004).

The examine engine irradiate (CEL) doesn"t provide you lot information, but the five most usual reasons why the light come on in most vehicles incorporate a faulty oxygen sensor, loose or faulty gas cap, faulty catalytic converter, faulty mass air flow sensor, or failing spark plugs and/or wires. To run a diagnostic will give you more information about why the light is on. This diagnostic tool, well-known as a code reader or scan tool, can additionally turn off the light, however unless you address and solve the underlying issue, the light will certainly come top top again after you"ve driven in between 25 and also 50 miles. Utilizing the tool is fairly simple and also if girlfriend don"t have one, you can acquire one at many auto parts stores.

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Figure 1. The CEL advises you the your Jeep"s on-board diagnostic system has actually detected a problem.
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Method 1 – utilizing an OBD scanner

Step 1 – find the data connect connector

The data attach connector (DLC) permits you to connect the OBD scanner to your Jeep"s ECU.

Make certain your Jeep is off prior to starting.Open driver"s side door and also reach under the dashboard. The DLC is situated on the much left side, towards the front and also slightly diagonal line to the steering wheel.Figure 2. Situate the DLC.Step 2 – connect the diagnostic scannerPlug the scanner right into DLC and then rotate on your Jeep Cherokee.Figure 3. Attach the diagnostic scanner.Step 3 – run the diagnostic scanTurn on the scanner and go come the appropriate screen because that diagnosing why your Cherokee"s CEL is on. The diagnosis might take a few minutes to totally run.When the diagnosis is complete, your scanner will generate a perform of codes details to what"s causing the light to come on. If you"re not acquainted with the codes and what they mean, her owner"s hands-on may incorporate this information. Create down the list of codes that your scanner produced after perfect the diagnostic scan.Figure 4. Wait because that scanner to pull up the CEL codes.Step 4 – Reset the inspect engine lightLeave the scanner associated to the DLC. The scanner will ask if you desire to erase all diagnostic results and codes. Choose "YES."Put your an essential in the ignition and also turn it come the "ON" position. Perform not start the engine.Press go into on the scanner once you"ve done this. The scanner will connect with her Cherokee and tell the to revolve off the CEL.Start the engine. The CEL should now be off.
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Figure 5. Confirm that you want it to reset the CEL.Figure 6. When computer has to be reset, the scanner will certainly let you recognize the code has been cleared.

Method 2 – Without utilizing an OBD scanner

Step 1 – Reset your examine engine lightDisconnect the hopeful (red) battery cable.Ground the hopeful battery cable to an unfavorable (black) battery cable for around 30 seconds.Reconnect the confident battery cable.Turn your vital into the "ON" position, yet do not rotate on the engine.Turn headlights on, and also leave lock on because that 10 to 20 seconds.Then rotate the headlights off.Turn your an essential into the "OFF" position, and also let the automobile sit for about one minute.Turn your key into the "ON" position, and then begin your engine. The CEL must now it is in off.

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Pro Tip

Resetting the examine engine light will certainly not deal with the worry that resulted in the CEL to which in the first place. If you execute not identify and resolve the issue, the CEL will most likely come ago on after you drive between 30 and 50 miles.