PO456 MIL (check engine) light code, please help.

[Surfslinger]

Scanner says PO456 which relates to the evaporative control... Checked for loose gas cap, polished the fuel inlet, reversed the cap gasket, etc, engine runs fine and I don't hear any vac leaks, see cracked hoses, etc...

For you folks who have had this same code and then fixed the problem, what was the cause? I'm guessing and hoping it is not one of the valves/switches, but would not be surprised if it were. Anyone know of a manual way to clear the code after I did all the gas cap stuff to see if that worked, or know how long/what driving parameters it takes for the code to clear itself after it detects a normal situation? Boy what a week. First I find coolant leaking around the water pump area, now this MIL today, and I just got my new PA plates yesterday which means I need an inspection and EMMISSION test within 10 days... MIL lamp on/code in computer at inspection = failure. Damn, this sucks!

Thanks for your help.

[jcurtin06]

go to autozone and have them clear it for you to see if it pops up again or disconnect the battery for 30sec, that should reset the ecu.

[Luna2]

Originally Posted by Surfslinger

Scanner says PO456 which relates to the evaporative control... Checked for loose gas cap, polished the fuel inlet, reversed the cap gasket, etc, engine runs fine and I don't hear any vac leaks, see cracked hoses, etc...

For you folks who have had this same code and then fixed the problem, what was the cause? I'm guessing and hoping it is not one of the valves/switches, but would not be surprised if it were. Anyone know of a manual way to clear the code after I did all the gas cap stuff to see if that worked, or know how long/what driving parameters it takes for the code to clear itself after it detects a normal situation? Boy what a week. First I find coolant leaking around the water pump area, now this MIL today, and I just got my new PA plates yesterday which means I need an inspection and EMMISSION test within 10 days... MIL lamp on/code in computer at inspection = failure. Damn, this sucks!

Thanks for your help.

Gas cap loose or leaking. (Do not fill tank with engine running.)

[njerald]

Just follow the diagnostic steps in your Service manual.

[Surfslinger]

Gas cap was tight, as I never refuel with the engine on. I flipped over the cap gasket, polished up where the gasket makes contact with the filler neck, and then disconnected the battery. car ran like crap during its "learning period", but after some pretty spirited driving is running fine w/o the MIL on as of tonight. It seems the MIL problem is solved, but I wonder if the code still remains in the CPU, and will cause me to fail the emissions test?

The PA law states "Basis for failure"

(E) Any DTCs (Diagnostic Trouble Codes) are present and the MIL (Malfunction Indicator Lamp/Check Engine Light) status, as indicated by the scan tool is commanded on, regardless of whether or not the MIL is actually illuminated.

So it looks to me that although the problem is fixed, and the light is off, that any lingering code in the computer will cause failure. I also understand that even if you erase the code, that in some way the inspector can tell that it was done before the car went through enough normal cycles, and you fail.

Anyone know how many ignition on/off cycles, miles driven, or other conditions that must be met before this stored code is erased?

Thank you.

[Luna2]

Go to Autozone and have them "reset" the computer to get rid of the codes or get one of your own. My code reader can do it and costs less than $90.00. There is a retest, "Pass or Fail" period, varies with the type of fault after the "Reset". No, I do not know of any other way to reset the MIL codes and erase the pending codes, except with a tester or reader.

[TRD VVTi]

It will pass now.