post #1 of Old 02-23-2008, 08:49 PM Thread Starter
fivespeedsteed
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help tracking down a code and evap system probs.

ok so i threw a code today - P4056 which is

Evaporative Emission Control System Leak Detected (very small leak)

description is :

(Also see Notes in P0455 above). Does customer regularly commute on a steep grade (down hill grades in excess of 10%? Has the Leak Detection Pump Operation and Diagnosis booklet (Publication No. 81-170-000606) been used to assist in the diagnosis?

Review and if necessary, perform TSB 18-010-02. Be sure to completely read the TSB. The fix for the condition is a PCM replacement, not a reprogramming of the controller. Be sure that there is not any leaks in the system. This TSB applies in a very limited number of cases and usually in mountainous regions. TSB 18-010-02 Is a PCM replacement correct an erroneous MIL illumination for SAE P0456 that sets when driven on steep grades.


what do you sugest i try first? i got this code once before and i looked at the evap canister under the hood and there was a hose that was leading from it that was cracked and i tookl it off and bypassed it and it went away after clearing the ecu. thanks for the help guys


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post #2 of Old 02-24-2008, 11:56 AM
silentbob21
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so is your prob fixed ? ive had this problem for a while now... havnt been able to get rid of it. kinda gave up dont feel like throwin money at it.

-Aaron

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post #3 of Old 02-24-2008, 01:22 PM
tsconver
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Try the gas cap, make sure seals are good and clean on it, if in doubt replace it. If that does not fix it then it is hunting time, could bea small hole in a hose or the actual pump, the pump is the small device on the drivers fender under teh hose right next toteh master cylinder. Check hose and it first.

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post #4 of Old 02-24-2008, 02:16 PM
silentbob21
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is the LDP the thing mounted to the side of the engine bay, has a plug going to it.... mounted on some rubber grommets.

I replaced gas cap twice, and replaced a hose that was cracked. all other hoses that I have seen look good. LDP or charcoal canister would be my next step but I dont want to pay $100+ for those parts... and them not fix anything

-Aaron

2004 WJ SE 4.0L I6, NV242, IRO 6.5 LAs D44a Spartan locked, 4.88s, BFG KM2s 35/12.5/15


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post #5 of Old 02-24-2008, 03:43 PM Thread Starter
fivespeedsteed
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i got this code before and i checked the evap thing on the driver side of the bay in the back and there was a h ose coming off it that was cracked so i fixed it, and reset the computer and it went away. i just had advance reset the computer again and it hasnt come back up. if it does ill look at that gas cap seal once more. thank you for the help.

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