dsteinaz

Last week my engine light went on and I realized that I left my gas cap at the gas station. No luck in finding it so I bought a new cap at a local parts store ( Not Porsche). I have driven the car for 5 days now but the light stays on. What sensor is telling the computer that the cap was off ? Do I need a new Porsche gas cap? Do I need to wait longer?

riozilla

I think you have to go to the dealer and they have to reset something.

I had to do that when mine was not closed all the way when my wife drove the car last...

1999Porsche911

If you replaced the cap with the correct cap, the light should go off in several drive cycles. If you want it off immediately, disconnect the negative cable on the battery for a few minutes and then reconnect. Depending on the year of your car, you may have to reenter the 4 digit radio code. Your car will run a little rough for a while until the computer relearns the proper settings.

bet

Are you sure the non OEM cap fits properly? A poor seal will cause the light to stay on.

clum553946

You need to get the OEM cap & drive the car for awhile so the computer can recycle itself.

Lorenfb

You can't reset OBDII fault codes by disconnecting the battery. Although, the
tank venting & leaking are part of the OBDII diagnostics, I wouldn't assume that's
the source of your problem, although the correlation is logical. I would:

1. buy an OBDII scanner for checking the faults & resetting codes, < $100 now
2. find an independent Porsche with the PST2 tester
3. go to a "big box" auto supplier & have them read the code
4. go to the dealer

Bottomline: Don't drive with the fault code present too long as you might have
a costly repair to deal with in the future.

Loren

Sorry, but that is not true. If you disconnect the battery (for at least 2 minutes) it will clear the light. The fault memory in the DME will be cleared only if the fault does not occur again within a specific number of engine cycles. If the fault does occur again then the light will come back on.

dsteinaz

Took the car to autozone, they scanned the computer, found out that it was in fact evaporation from the gas cap being off and reset the CEL. Took about 4 minutes and they didnt charge me a cent.

Lorenfb

"If you disconnect the battery (for at least 2 minutes) it will clear the light."

As I said; "You can't reset OBDII fault codes by disconnecting the battery."
The fault memory uses flash memory technology which is non-volatile to Vcc (battery voltage).

"Took the car to autozone, they scanned the computer, found out that it was in fact evaporation from the gas cap being off and reset the CEL. Took about 4 minutes and they didnt charge me a cent."

Great, that's the way to solve the problem, the right way.

Loren

Please reread my post - I am not trying to start an argument here. There is not a "right way" either method will work. My point is that if the cause is not corrected then resetting the light will do no good as it will just come on again.