Drove without oil cap on...

Thanks for posting the article. I have a 2002 330ci with 99,908 miles when the "service engine soon" light came on and the car has a rough idle but still has decent power. I had AutoZone check for codes and they found four. They are P0171, P0174, P1342, and P1348. When I returned home I discovered I had left the oil fill cap off. My guess is that I drove the car between 170-200 miles like that. Thoughts? Oxygen sensor and or mass air flow sensor? Thanks for the help.

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: About Oxygen Sensors

[Wayne 962]

Other than creating a big mess in the engine compartment, there's no real damage that can be done by driving without the oil cap properly attached. I will admit that I did that once too, and paid for it by having to clean the whole engine. The car is expecting there to be crankcase vacuum, so when there isn't, it will pop codes and run rough. Install the oil cap back on if you haven't already, reset the codes, and then see if they return.

- Wayne

[TomInGA]

Thank you for the response. I reinstalled the oil fill cap and removed the gas cap and reinstalled. The service engine soon light was still on after a 20 mile drive to work this morning. When I started the car at the end of the day, NO service light!

Hopefully my stupidity will help someone else avoid unnecessary repair cost.

Tom