I did my 3rd oil change today at 10k. I put in 4 1/2 quarts, oil and filter purchased from my dealer. Later in the day I started the car up only to notice the idle bouncing back and forth between aprox 600-1000rpm. I though that seemed a little odd, but didn't worry about it. The car ran fine, but gave the odd idle symptoms again after my next start up, only this time it gave me a CEL. I popped the hood and found that I had not fully seated the dipstick. It has an o-ring that seals it in place. I suspect this to be the cause of my problem, but don't really know for sure. Has anyone else experience this?

 

I had a similar idle on my 07 MC last summer. Only happened about 3 times. Problem seems to have gone away. Dealer never figured it out and it never happened with him and I had him keep it twice for a week. They wrote it off as bad gas, gave me some fuel system cleaner and recommended a brand change. Hasn't happened since. I've kept my eye on this kind of behavior and only seem two other posts like it. The other one was a loose oil filler cap. I never got any sort of CEL when my weird idle occurred.

 

No CEL this morning, it reset itself.

 

vacuum leak via dipstick hole will do that.

 

That was my suspicion. Thanks R56mini.

 

A CEL should "throw a code" which can be read either by an external scanner (your local autoparts store can plug one in for you), or on the R56 I understand you can get 'em from the OBC's "Service Check" test. So you should be able to obtain the code if it still logged in the OBC.