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Ron Z.
Ron Z., - Jeep Tech -
Category: Jeep
Satisfied Customers: 18117
Experience:  18+yrs experience. State Inspector & Jeep Diagnostics/Repair
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My 2007 Jeep Grand Cherokee's malfunction light is on. Comes

Customer Question

My 2007 Jeep Grand Cherokee's malfunction light is on. Comes on once in a while and then goes off in a few days. Do you know why?
Submitted: 1 year ago.
Category: Jeep
Expert:  Ron Z. replied 1 year ago.

Sorry for the delay in getting to your question...

Did you happen to have any of the Diagnostic Trouble Codes (aka "P-Codes") scanned from the computer when the MIL was lit?

Customer: replied 1 year ago.
no. just the image which the manual says is a malfunction alert. it is a yellow image that looks a bit like outline of the vechicle.
Expert:  Ron Z. replied 1 year ago.

Ok, great. This is the Malfunction Indicator Light (MIL) also known as the Check Engine Light. Unfortunately, there are literally hundreds of parts and sensors monitored by the on-board computer, that when faulty can set this light. If the light is intermittent and there are no drivabilty or performance issues when the light is on, more than likely, the problem will lie in the EVAP (emissions control/recovery) System, or is a sensor that isn't used until needed- like the internal heater for an Oxygen Sensor. So, at this point, we'll need those P-Codes before we can even begin to take a guess as to what the root of the problem is. So, next time the light comes on, you have a couple of options:

1. Most Jeep models with a digital odometer can run a self-diagnostic.

Get in the vehicle, and close all the doors. Without starting the engine, cycle the ignition ON-OFF-ON-OFF-ON within 5 seconds. Where the odometer is should now be displayed "p-codes" (ie. P0123). Make sure to end in the ON position, and do it quickly- within 5 seconds.

2. You can have these p-codes read FREE (except in California) at any local "big chain" part store (ie. AutoZone, PepBoys, Advanced, etc).

Once we have these p-codes, we can more accurately and efficiently diagnose the problem and then make the correct repair.

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Expert:  Ron Z. replied 12 months ago.

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