Engine check light went OFF on its own after one week

Liberty for All · **Posted:** Mon May 11, 2009 12:02 am

Can some engine check light problems clear up , turn off the dash light, without doing anything?
Has this happened to anyone's?
In the past I have had a code mentioning a slight vacuum leak in the exhaust evaporation system and canceled the code with my reader.
This past week I did not have time to diagnose the latest check light when it turned off by itself.
Experience, suggestions, warnings from anyone?

:roll:

LibertyTC · **Joined:** Tue Apr 14, 2009 3:48 pm **Posts:** 27

Sounds Like code P0442. Loose or after market gas cap not sealing properly allowing fumes to escape Cap pressurization. I just replaced with a Locking Jeep /Chrysler Gas Cap /cleared the code by removing the negative battery cable for 10 min. So Far CE light has not come back on.
I also checked all of the hoses for cracks behind and around the fuel tank, which were all in good condition.
The CE light can turn off, if it no longer detects malfunction, but I prefer to make repair and turn it off myself/clear code so the CE Light wont burn out.
When you fill up click the cap 4 times to ensure it is tight and don't use aftermarket locking cap, I learned the hard way.
You can also read the CE code in the Liberty from the digital Odometer without a code reader. Simply with in 5 seconds turn ignition key:
On/OFF - On/OFF- ON. (leave on) then...
Since your CE Light is on, it will show P0442- DONE. If there are multiple codes it will show all the codes one by one then Done.

Liberty for All · **Posted:** Tue Jun 16, 2009 4:25 pm

The code reads 0456.
Where is the listing of codes on this site?
What is the meaning anyone here can advise me how to fix.

Thanks people! :?:

tomsjeep · **Posted:** Tue Jun 16, 2009 5:31 pm

Evaporative Fuel something or other...
http://www.obd-codes.com/p0456
From the link above:

Quote:

First, using a scan tool activate the vent solenoid, sealing the system. Then monitor the fuel tank pressure (FTP) sensor. If the system is sealing properly, the number will stay consistent. If is isn't, the pressure sensor will show that as well. If the system slowly leaks, use a smoke machine and watch for smoke exiting the system at any EVAP component. Any where there is smoke exiting the system, that is the faulty component. Do not pressurize the EVAP system with air pressure. Doing so can damage the purge and vent solenoids in the system.

Liberty for All · **Posted:** Tue Jun 16, 2009 8:45 pm

Last Spring I had the same code. I bought a Stant locking gas cap and tightened up a little on one of the connections entering the Evaporation Canister. I erased the code with my code reader and no worries until a month ago when the light was back.
Thanks for the referral web site. Is this a recurring code for many of our Liberties? This system should not have problems on a relatively new vehicle.

tomsjeep · **Posted:** Tue Jun 16, 2009 9:33 pm

Loose gas cap is a different code... and the really common one (on both my Jeeps)... this one can fool as it behaves like the loose gas cap thing... I was getting torqued at my local filling station guy for being sloppy 'til I checked the code on mine a coupla years back.
I agree that it's not common for a newer vehicle, at least I don't think so. It is sometimes indicative of one of the sensors going out.

KJ in CO · **Joined:** Thu Apr 09, 2009 4:06 pm **Posts:** 346

I would check the HO2S (heated oxygen sensor) before the catalytic converter to see if the wires might be worn through from hitting your driveshaft. Problem I had just recently. Or, take it to the auto part store and use one of their OBD2 system scanners and it will tell you what sensor(s) are sending the codes and they should know what the codes signify. There arent many things it can be in the emission control system. Oh yeah, you should go in and erase the old codes while you are at it, they do store in the system until erased, at least mine did, even though the check engine light was off.

KJ04 · **Posted:** Thu Jun 18, 2009 5:32 am

P0456 is EVAP system small leak.

Anyone throw a P0441? EVAP purge system performance.
If so, what was the fix?

ZERO6 · **Posted:** Mon Jul 13, 2009 8:51 am

I had that prob aswell, was a $2.00 hose the cracked
in the engine compartment.
Hope yours was that easy..

TruLiberty · **Posted:** Mon Jul 13, 2009 10:14 am

cant wait to try the on off to show my code.

it goes on and off every 3 days or so, stays off for a week or more.

Engine check light went OFF on its own after one week

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