andover

Above car with ~10.8k miles (yes, I know) Bought from dealer in Nov. '18.
Fully inspected. R/R'ed many items, mostly calendar.
While local driving this a.m., CEL comes on. Stopped by the a local non-dealer Porsche shop and a quick check showed both P171 & P174.
Engine idles smooth, accelerates fine. Have not got it up to speed though.
Checked fuel cap - open & closed tight. Still throws the CEL.
About to head off on a 4 day trip tomorrow. Shop can't get to it today.
Any thoughts?
Thanks

Psychopoodle

Might be some starting points here:

P0171 Oxygen Sensing Adaptation, Idle Range, Bank 1 – Above Limit
P0174 Oxygen Sensing Adaptation, Idle Range, Bank 2 – Above Limit

Possible fault cause
- Incorrect signal from MAF sensor
- Intake air system leaking
- Fuel pressure too low
- Volume supply of fuel pump too low
- Fuel injectors fouled
- PCV valve leaks
- Cap of oil filler neck not closed correctly or seal is damaged

andover

"Cap of oil filler neck not closed correctly or seal is damaged"
I'm going to go with that. Put 1/2 qt. in last night.
Previously owned a Cayman S, so was surprised to see the "tube extension."
Thought it was tightened but I guess not. Unscrewed/rescrewed the cap twice, seems to be tight. Got the last little "dull click."
Give the man a cigar. Thank you "Psycopoodle."

Now, how do clear the CEL? Or just drive?

andover

Will try the local auto parts shop and then just drive.
If not out by the time I get back home, then I'll stop and see the shop.

andover

Psychopoodle

Glad to hear it worked out! That was definitely the most benign possible cause. I'll be paying more attention to my oil cap now as well.

Greenchunks

I had the same issue when I bought my car and drove it back. I added a quart of oil and didn't seal the cap. The car started idling rough and at 1500 rpm, threw the P0171 and P0174 codes. The next morning I resealed the cap and the following day the CEL went away.

Bruce In Philly

2009 C2S 130K miles

Yea, I threw codes ..... screwed on the oil cap crooked... how the heck you do that is beyond me but I did.

Peace
Bruce in Philly