Hey guys, my "check engine" light came on yesterday after I put a half tank of 91 grade gas from Shell, no messages on the iDrive though...I've done searches and read topics in the forum but still am unsure, help please! :help:

You need to have a OBD II code reader to find out whats going on. If you have an autoparts store close to home such as Autozone, they will read the code for you free of charge. Find out what the code is and someone here will be able to help you figure out whats up.

Check the gas filler cap, it may not be tightened properly after the fill-up.

+1 ^

HTH,
Jim / crewzer

I agree, sounds like filler cap is not tightened properly also it might be time to change O2 sensor! :dance:

So I checked every cap there is that I can see, still no luck, now I notice my car idles pretty rough, the rpm drops just a tad like its pulsating producing more vibration and seems like its about to stall, I'm a nervous wreck... :help:

Mine was stumbling and actually cut off with a check engine light. I turned out to be a low pressure fuel sensor on a 535 not sure if this is a common part. OBD code said Fuel pump plausibility...

Best to go to a Pepboys or something and have it scanned

without the code, you never know what it can be

These days you can buy an OBD-II code reader for under $40. So, there is no reason not to own one.

Step ZERO (prior to step 1) in automotive diagnostics is to read the diagnostic code(s).
I wish human body also sets those codes :-)

Great advice! We can guess all we want and throw money at possible fixes, but there is nothing like tackling the exact problem and knocking it out the first time.