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Unread 05-06-2013, 05:35 PM   #1
shatteredsoul
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1998 TJ Wrangler 
 
Join Date: Mar 2009
Location: Portland, Tennessee
Posts: 737
2011 GC check engine light

The CEL came on today on my wifes 2011 GC with around 45,000 miles, its throwing code PO455 for the evap system. She is pretty good at making sure the gas cap is tight when getting gas.

Whats the chances the cap is bad? or would it throw this code if the cap is left loose 1 too many times? She said she did leave it loose once when she first bought it but that a small gas cap light actually lit up on the dash telling her it was loose. Also is there a way to clear the code without a scan tool? The Jeep is just out of warranty and Im trying to keep it away from the stealership if possible. To add to that the timing cover is ever so slightly leakingfrom the RTV sealant so it will end up at the dealer under the powertrain warranty to fix.

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Unread 05-07-2013, 11:41 AM   #2
JeepCares
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Join Date: Jan 2012
Location: MOPAR World Headquarters, Chrysler Group LLC
Posts: 2,501
I can't specifically answer your questions as I am not technical but here is some info from the 2011 WK Factory Service Manual:
(ignore if not helpful)



P0455-EVAP PURGE SYSTEM LARGE LEAK


Theory of Operation

The Evaporative Purge Monitor tests the integrity of the hoses/tube between the throttle body/intake and the fuel tank. The monitor is a two stage test and runs only after the Evaporative system passes the small leak test. Stage one is non-intrusive. The Powertrain Control Module (PCM) monitors the purge vapor ratio and the Evaporative System Integrity Monitor (ESIM) Switch closed ratio. If the purge vapor ratio is above a calculated value, the monitor passes. If the ESIM Switch closed ratio is greater than calculated value when purge flow is greater than a minimum value, the monitor passes. Stage two is an intrusive test and runs only if stage one does not pass. The PCM commands the purge solenoid to flow at a specified rate to force the purge vapor ratio to update. The ratio is compared to a calibrated specification. If it is less than specified, a one trip failure is recorded. This test can detect if the purge hose is off, obstructed or the purge valve is not operational.


When Monitored:
With the engine running, during a cold start test with the fuel level above 12%, ambient temperature between 4 C and 32 C (39 F and 89 F) and the fuel system in closed loop. The test runs when the small leak test is maturing.

Set Condition:
The Powertrain Control Module (PCM) activates the Evap Purge Solenoid to pull the Evaporative system into a vacuum to close the ESIM Switch. Once the ESIM Switch is closed, the PCM turns the Evap Purge solenoid off to seal the Evaporative System. If the ESIM Switch reopens before the calibrated amount of time, a large leak error is detected. Two Trip Fault. Three good trips to turn off the MIL.


Possible Causes
EVAPORATIVE PURGE SYSTEM LEAK
EVAP PURGE SOLENOID
EVAPORATIVE SYSTEM INTEGRITY MONITOR SWITCH


Note: A loose gas cap could have caused this DTC to set. Make sure gas cap is tight and in good condition. Make sure the gas cap meets OEM specifications.
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Lee
U.S. Top Care
Chrysler Group LLC
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