My wife had the CEL come on this morning. She drove to a class about ten miles away, came out 90 minutes later and the light came on upon starting and stayed on.

I removed and replaced gas cap securely. No change.

She is at 40,800 miles, and 8,200 since last service. OBC says 68 days till service.

Coincidently, or not, yesterday i topped up the oil with M1 0-40 euro formula oil. It was near the bottom of dipstick, and is now just barely below the full line.

Any suggestions other than a trip to the dealer?

TIA.
David in MD

Lots of software fixes for late model MB's. Seems like a new issue pops up every week. It looks like your under warranty so why not take it to the dealer???

My dealer is always trying to up-sell service, so I only go for the required intervals. They are also kind of a PITA to get in and out of.

Tell 'em you want a loaner along with pick-up and delivery. Can't hurt to ask.

So, I am now driving a loaner. They "re-flashed" and got rid of the check engine light, but can't tell me what caused it. Meanwhile, i had noticed a bunch of grease all over front left wheel. The CV boot has apparently failed. The tell me a new cv joint had to come from Germany, so 72 hrs in transit. I took the car in Wed am, hope to get it back Monday.
Thanks for your replies ILUVMILS

Nothing unusual there. Germany is constantly upgrading software for various systems and they rarely share their "bug list" with the dealers.

Thank you ILUVMILS for reading my rant.

The service receipt states:
"DTC P045100 Could not duplicate cause of code at this time"
Not really much of a surprise, as you say.

I was pretty ticked off about the service after picking up the vehicle last night. The dealer had my car 7 days & 6 nights. The service adviser told me in plain English that the ordered "CV Joint" was the cause of the delay. I was told the part arrived late Monday. The service was finished Tuesday afternoon.

I think many Service Advisers are mechanically clueless.

It turns out they were not waiting for a CV Joint, only two rubber boots.
UFB! I can't believe a rubber CV boot set is not a fairly commonly used part that would be readily available.

Oh well, at least I caught it before the warranty expire.