# XJ Check Engine



## SeaSalt (Apr 29, 2002)

Check engine light just came on my XJ.  What should I do?


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## BubbaBlue (May 11, 2004)

You have to take it somewhere so they can read the computer error code. Could be lots of things. Emissions sensor, gas cap loose, who knows? Most of the time it has something to do with the emissions system.

Heard you can get it checked for free at an Auto Zone or Advance Auto, but I've never used them.
.


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## 1BadF350 (Jul 19, 2006)

Check your engine of course.


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## surfcast (Nov 7, 2006)

They will ..I've had them do it at Advance before..Mine turn out to be those pesky O2 sensors.


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## Mullet Breath (Nov 15, 2006)

*gas cap*

I'm sure you know this, but if your gas cap is not turned enough to click a few times, or the cap's gasket goes bad it will cause that. If you, haven't try twisting your cap a few clicks, disconnect the battery a few minutes then hook it back up and see if it goes away. Just a thought for you, and a heads up to anyone who doesn't know that.


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## SeaSalt (Apr 29, 2002)

Mullet Breath said:


> I'm sure you know this, but if your gas cap is not turned enough to click a few times, or the cap's gasket goes bad it will cause that. If you, haven't try twisting your cap a few clicks, disconnect the battery a few minutes then hook it back up and see if it goes away. Just a thought for you, and a heads up to anyone who doesn't know that.


thanks guys. I think I'm going to have to check the gas cap because my wife filled my jeep pass weekend. Hopfully, this will solve the problem.


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## bivalvebill (Feb 10, 2007)

Save your self some money and take the bulb out. Just kidding 9 times out of 10 it is an evaprative emissions code which translates to a loose gas cap or o2 sensor problem. good luck


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## BLUESMAN (Nov 4, 2003)

*Read the code yourself:*

If you go on the jeepsunlimited website, XJ or TJ forum and search for error codes you'll see how to get the code through your odometer and ignition switch. All the engine and system codes are listed there. At least that way you'll know if some mech is trying to rip you.
opcorn:


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## Bull Durham (Aug 14, 2006)

The check engine light came on a couple of weeks ago in my S-10. Took it to the shop, cost me $49.00 to find out my cigarette lighter fuse was blown. :--|


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## Lip Ripper (Dec 8, 2003)

dont know about the xj but in my yj you just turned the key on and off 3 times on the third you leave it in the on position, then count the times the safety belt signal flashed, then look that number up in the chiltons book. like (12 flashes= throttle positioning sensor). then you had to take the battery terminal off for 30 seconds to reset the check engine light. it was cheaper than taking it to a mechanic.


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## SeaSalt (Apr 29, 2002)

I just went to Advance Auto and got the code. Code is p0455 Evap Major Leak.

I got a new gas cap and the check engine is still on. I might have to take it to my mechanic.  

I've checked the evap canister infront of the rear axle, didn't notice any cracks in the 3 rubber tubings or the connectors. I might have to get a smoke test done by the mechanic. Hmmm....

Pic of my evap canister


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## Dae (Jun 25, 2002)

SeaSalt said:


> I just went to Advance Auto and got the code. Code is p0455 Evap Major Leak.
> 
> I got a new gas cap and the check engine is still on. I might have to take it to my mechanic.
> 
> ...




I can't remember if it's true or not but I do remember on some vehicle, you need so many restarts before the code will disappear. You could also take it to a place with a scanner and have them reset the code. If it comes right back, you know you still have a problem. 

I do know whenever I've had a check engine light on my XJ, it's always been the O2 sensor.

- Dae


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## narfpoit (Jun 16, 2004)

Dae said:


> I can't remember if it's true or not but I do remember on some vehicle, you need so many restarts before the code will disappear. You could also take it to a place with a scanner and have them reset the code. If it comes right back, you know you still have a problem.
> 
> I do know whenever I've had a check engine light on my XJ, it's always been the O2 sensor.
> 
> - Dae


My wife's civic is like that you need to give it a couple days and it will reset itself


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## BubbaBlue (May 11, 2004)

Reading material:

http://www.car-groups.com/post/28429/Dreaded_P0442,_P0455_on_

http://www.wjjeeps.com/faultcodes.htm

http://www.jeepaholics.com/support/topic.asp?TOPIC_ID=37851

http://www.cert.ucr.edu/research/pubs/EPA-SCAQMD-OBDII-final-5-01.pdf

.


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## SeaSalt (Apr 29, 2002)

thanks bubba! I'm going to attemt to go under my car again and look for leaks in the tubings...


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## hengstthomas (Mar 11, 2006)

Dont know if this will help but my check engine light comes on when I start the truck and leave it idling for more than 10 minutes (got to be a sensor) so as long as I dont initially warm the truck up I have no problems. I know it probably something simple but it doesnt have an impact on the truck at all other than the obvious eye sore....Its been almost 3 years and still no problem. Just disconnect the battery and its gone. Had it affected the drivability it would be fixed but if it aint broke ? I was told it was abuild up of carbon that caused the EGR valve to stick open but I opened it up and removed the build up(there was a big piece slightly holding the spring open) and the light is still on.


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## SeaSalt (Apr 29, 2002)

its like magic... check engine light just disappeared. I'm sure it will re-surface someday... until then I'm a happy camper.


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## narfpoit (Jun 16, 2004)

SeaSalt said:


> its like magic... check engine light just disappeared. I'm sure it will re-surface someday... until then I'm a happy camper.


Then it was just the gas cap. If it ever comes on again especially if you recently filled up then just make sure your gas cap is tight.


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