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First time Porsche (hopefully not last time, lol) owner here.
Purchased a dealer serviced 2012 Cayenne S with 50k miles. It drove fine for the first 3k miles but then started to act up.
First, the PSM failure light went on but it would go disappear after turning off the engine. It doesn't happen on every drive. Within a week my check engine light went on. I purchased an Autel scanner and a P0303 Cylinder 3 misfire was detected but didn't say anything about the PSM failure.
How should I approach diagnosing my problem?
I was thinking of either replacing the ignition coil and spark plug on cylinder 3 to see if the problem will go away or swapping the ignition coil and spark plug on cylinder 3 with a different cylinder.
Or do you think with the age of the vehicle, I ought to do a tune-up anyways and change out all the spark plugs and ignition coils?
Being a 2012 how old is the battery? May not be related to both issues but is a good starting point if there are any electrical gremlins.
Plugs could original and are supposed to be done at 40k miles following the owners manual service schedule, may not hurt to swap them out if you don’t have the history
Would the check engine light disappear on its own if I swap out the spark plug and ignition coil and it turns out to be the cause of the problem or would I have to reset the codes first?
I'm dusting off the cobwebs here, but I'm pretty sure that a Porsche service advisor told me that the PASM will automatically disable if there's engine trouble. It's a protective measure.
Yes clear the code and see if it returns. It could also be battery as others have suggested. Likely culprit is one of the two so you should be pretty close to resolving if not already.
09-20-2022, 05:03 PM
Q about PSM failure, then cylinder misfire
