Codes on Expedition
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Codes on Expedition
My check engine light is on and I had the codes read. The code that was listed is the DTC PO455, EVAP Emission Control System Leak (Large). I had them read at Advance Auto Parts. The guy didn't really know what the problem was. Do you have any suggestions as to what I should do now? Any help is appreciated. It is a 1998 Ford Expedition, Although I am looking at the little paper where the codes are listed and it says Vehicle scanned as a 1999 Expedition. Would that make a difference?
Thanks,
Eddie
Thanks,
Eddie
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Joined: Mar 2004
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From: Grand Island, NY
The most common cause of that is a open, leaking,or bad gas cap. Gasoline will left in an open caontainer will Evaporate over time "EVAP". These fumes go into the atmosphere creating pollution. The Federal Gov made a rule that the fuel system must not leak fumes to the atmosphere OBDII regulations. Basically you fuel system is vented through a charcoal canister when needed. You cars computer will ocassionally test the system, It will close the vents, use engine vacuum to draw a vacuum in the gas tank, close the vacuum valve and uses a pressure sensor to make sure the vacuum stays at a certian level. If the gas cap was bad or not on you would get a large leak, if the vent valve could not close you would get a large leak, if one of the many hoses was off or damage etc. They do make testers for the gas cap or give it a few days making sure it is closed. A shop would use the service port in the EVAP system to draw a vacuum and go through the system looking for leaks or bad sensor reading, solenoid not engaging etc.
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Joined: Mar 2004
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From: Grand Island, NY
Tough call being a 99 a Ford dealer probably has seen many and there may be a common part of the system that is the culprit and they can find it fast, hopefully not much labor "cheap". I good local mechanic should be able to trouble shoot it. How long has it been going on ? you may try and give it a week or two and see if it goes away. You should have no driveability problems and will not hurt or make anything worse. There is also a code for small leak, those are tougher to find and could be a loose hose clamp somewhere. Ask some local shops tell them you have a large EVAP leak, if they moan and groan go somewhere else, if they seem confident they probably know what they are doing.
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Gas cap
I checked the gas cap last night and it was not twisted on. My girflfriend had gased up the vehicle a few days ago and told me that she just put the cap on top and didnt tighten it. Thank God for that plastic retainer that attaches it to the gas tank. I think the check engine light should go off after we drive it for a day or so. Thanks for your help.
Eddie
Eddie
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Joined: Mar 2004
Posts: 219
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From: Grand Island, NY
That would explain large leak, it should turn off the light after it runs the test again. Another tip for the EVAP system is never try to put too much gas in, when the pump clicks off stop, do not try to squeeze in more fuel and fill the filler neck. The reason is liquid fuel can get into some of the vapor lines where sensors and solenoids are and create problems. They have had so many people go to dealers for loose gas caps that new vehicles light up a gas cap symbol instaed of a check engine light for that code.
