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Unread 06-23-2006, 11:15 PM   #1
avpro91
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2003 JGC Engine Light keeps coming on

I have a 2003 Grand Cherokee Laredo and after about a year, the check engine light came on. Took it to the dealership and turned out it was a loose gas cap. No problem, my fault. Then it happened again about six months later. Same thing again, but this time I'm sure the gas cap was tight. Dealer said the cap might be bad. So a month later it came on again. Changed gas cap at advice of dealer. Now the light will come on within a day of resetting it. I'm convinced its not the gas cap...and it runs perfectly fine. Ive just left the light on for about a year now. Is there some other sensor in the system that anybody knows about that will keep this light on? Any ideas would be appreciated. Ive heard this is a common problem.

I tried checking for a code by holding the odo reset and turning on the ket, but none showed up. Going to try the code reader at Autozone tomorrow.

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Unread 06-23-2006, 11:19 PM   #2
10achik
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turn the key on (to acc) then off three times then read the codes, you don't have to push the odo button. My guess is an O2 sensor is keeping it on. Read the codes then post back or go to www.wjjeeps.com
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Unread 06-23-2006, 11:59 PM   #3
avpro91
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Thanks. It came back with P0455.
Which I believe is a large leak has been detected in the evaporative system. This would make sense is a gas cap was loose i guess. But I make sure the darn thing is on tight, and when i reset the light, it will come on again without ever taking the gas cap off. Like i said, I have already replaced the gas cap. Any idea what else would cause this message???
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Unread 06-24-2006, 12:12 AM   #4
-Joe-
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Causes

A code p0455 most likely means one or more of the following has happened:

* A loose or improperly affixed gas cap
* A non-conforming gas cap (i.e. not factory/original brand)
* Other leak or damaged piece in EVAP system

Possible Solutions

With a p0455, the most common repair is to:

* Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
* Otherwise, replace the gas cap, and/or
* Inspect the EVAP system for cuts/holes in tubes/hoses (you may hear a vacuum noise or smell fuel), repair if necessary


Which you already knew. I would check the hoses going to your evap cannister if you have one.
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Unread 06-24-2006, 12:14 AM   #5
10achik
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I agree, if you are absolutely sure the gas cap is new and sealed properly (you can go by an emmisions testing place and have it checked) then I would suspect a tiny hole in a hose.
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99 GC Limited - 4.7L HO V8, 6.5" IRO HC LA lift, F&R D44s locked & trussed, 242HD, IRO TC Skid, KMA Bumper, 35's
2006 Saturn Redline -2.0L Eaton supercharged I4, GMPP Stage 2, Custom Tune, AEM CAI, Ebiach Pro Kit w/ swaybars, EVO Ventus V12s (13.76 @ 103.85)
2006 Pontiac G6 GTP
2012 Nissan Juke - (hers)
2000 SV650 - naked, integrated tail light, sliders, corbin, pilot roads, RK chain & sprokets, D&D full exhaust, FactoryPro Stage I jet kit, +4 Ignition Advancer, Barnett race clutch
2006 Triumph America 900 - Full Dresser

January 2009 Grand Cherokee of the Month (GCOTM)
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Unread 06-24-2006, 12:16 AM   #6
ArloGuthroJeep
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First time I have seen it report a "large" leak...99% of the time it is a small leak. With a large leak you should be able to hear a vacuum as the fuel pump tries to de-pressureize the tank...
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Unread 06-24-2006, 12:25 AM   #7
avpro91
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Thanks for all the replies. I guess its on to trying to find a leak in the system. I'll check it out tomorrow. I read a service bulletin from Chrysler on the website 10achik listed and it listed a LDP valve as a possible culprit. I see if I can find it tommorrow and check it out. Again thanks for the help. Anything else you can think of / hear of would be great. Heres a copy of the TSB I found.


2500102A - MIL ILLUM., DTC P0442, P0455, OR P0456 - LEAK DETECTION PUMP, LEAK DETECTED
Date: 9/02/02 (supersedes 2500102 dated 2/11/02)

Model Year(s): 2002

Description: This bulletin involves a new diagnostic test for the LDP system.

Details: MIL illumination with one of the following DTC:
P0442 EVAP Leak Monitor .040 Leak Detected (Medium Leak)
P0455 EVAP Leak Monitor Large Leak Detected
P0456 EVAP Leak Monitor .020 Leak Detected (Small Leak)
If one of the above DTC’s are present, perform this diagnostic test first before proceeding with the diagnostic procedures in the appropriate Powertrain Diagnostic Procedure Manual.

Raise the vehicle on an appropriate hoist. Locate the LDP vent valve. Remove the vacuum hose from the top of the vent valve (Fig. 1). Attach a hand vacuum pump to the vent valve and apply 20” Hg. vacuum. Observe the vacuum for 10 seconds. If the vacuum holds between 15.5” Hg. and 20” Hg., refer to the appropriate Powertrain Diagnostic Procedure Manual, MDS2, or the Leak Detection Pump Operation and Diagnosis booklet (Publication No. 81-170-000606) for further diagnosis. If the vacuum drops below 15.5” Hg., obtain the appropriate LDP vent valve using the Mopar parts catalog and perform the Repair Procedure.

Repair procedure:
1. Remove the left rear wheel.
2. Remove the wheelhouse splash shield (five plastic rivets P/N 34201631) to gain access
3. Remove the hose at the top rear of the evaporative canister to ease vent valve removal.
4. Remove all clamps and all hoses attached to the vent valve.
5. Install new vent valve. Ensure all hoses, clamps and the vacuum hose to the top of the vent valve are securely attached.
6. Attach the hose at the top rear of the evaporative canister.
7. Install wheelhouse splash shield using five plastic rivets.
8. Install left rear wheel (WJ only).
9. Lower vehicle.
10. Use the DRBIII® to erase the DTC.

Parts required:
4669865 LDP vent valve



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Unread 06-24-2006, 12:34 AM   #8
avpro91
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Ummm.....anybody know where the LDP vent valve is located and what it looks like?
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Unread 06-24-2006, 12:40 AM   #9
ArloGuthroJeep
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I am too tired to post a pic, but it looks like it is directly behind the bumper of the rear left wheel well.
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Unread 07-11-2006, 10:09 AM   #10
avpro91
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Arlo- Any chance you can come up with a pic of the valve now. Im getting ready to crawl under there and it would be great if I knew exactly what I was looking at. The dealer was not interested in helping me witht the problem, so I figured I'd take the action recommended in the TSB and see if I could find the problem myself. Thanks.

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Unread 07-11-2006, 10:11 AM   #11
avpro91
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If anybody knows where I can get a schematic or a copy of the pages needed out of the service manual, that would be appreciated. Thanks

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Unread 07-11-2006, 12:20 PM   #12
nierace
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Why are you doing this ? You have a 7yr 70,000 mile warranty, bring it to the dealer ! Being it makes the Engine Light come up that would definately go under the PowerTrain warranty...
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Unread 07-11-2006, 01:29 PM   #13
avpro91
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Well, the dealer said that this is not covered under the power train warrenty becuase this is a problem with the evaporative system...not the powertrain.
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Unread 07-11-2006, 01:32 PM   #14
ArloGuthroJeep
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PM me in 3 hours (not now - that way I am at home when I get the PM) and I'll look up the pic and post it again.
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Unread 07-11-2006, 02:21 PM   #15
nierace
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Thats insane...is there another mopar dealer you can go to ? Doesnt have to be jeep...
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