Hi

Yesterday the check engine light came on on my Jeep '99 4,7 V8. There is no problem starting the car and I can't find anything wrong when I drive it.

There is no error code showing, I used the on/off method but I could not see any codes. Does that method not work in the '99 model ? Does anyone know how I can generate these codes ?

Thordur

I found the error code, it's P0442. That indicates some leak in the evaporative emission control system.

Check to make sure your gas cap is on tightly/correctly. That's the first thing to check when you get a check engine light.

This happened on my 2003 JGC a couple weeks ago and I paid $60 for the local mechanic to get the fault code. It came up as an evaporative leak, he told me to tighten my fuel cap, reset the code and took my money. The other day it come on again. I'm going to try the on/off method this time, but the mechanic told me that only worked on models before '96 or something. If you ask me, he probably knew that for $60 I could have bought my own code reader on the internet and reset the light myself.

Chad

Hi I used the on/off method on my jgc '99 so your mechanic is not telling you the truth. The light just disappeared without me doing anything.

The on/off method worked for me today and I got the codes P0442 and P0456, both small evaporative leak codes. I can't get my fuel cap much tighter, though. Guess I'll just wait to see if the light goes out this week.

Chad

I am sorry but you can not get codes on OBDII cars wothout scan tool. The scan tools you buy at store or online only read Generic codes. You have to have scanner to turn off evap code. This code will not clear itself. There are some that will but not the one. This is an emmisiion code. This is also a Generic code in this case. PO codes are Generic and P1 are dealer specific codes. And yes a gas cap can cause this code if left loose. But that is not the only thing. Best pactice is to have code cleared and then if it resets then there must be another leak somewhere. You can go to top of this page and read about Auto Tap, this should answer any misinformation.

Oddly enough the on/off method gave me those codes (2003 Jeep GC) without the cost ($60 in my case) of a mechanic to scan it. Those are the exact codes the mechanic got two weeks ago when the OBDII light came on before. I realize I cannot reset the codes without a tool, and the codes may be generic, but there they are -- and without the $60 in the mechanic's pocket. I suspect the problem may be a faulty gas cap (it's been on tight for weeks now) or another problem somewhere in the system.

Chad

Cool , sounds like a winner. I will try to remember that someone with 30+ years of experience doesn't count for anything. The lack of training. The lack of putting out good hard money to be able to make Diagnostic repairs isn't worth anything. Oh yea I guess you work for free.