DC Ross

Hey all,
I have a 2009 CLK 350. It's been running fine (even yesterday). Went to start it today, it turned over but didn't catch. I tried jumping it from one of those portable jump things. After the 5th or 6th try, it finally did start, but idled really, really roughly and the Check Engine light was on.

Any ideas???

Thanks much

Glyn M Ruck

Get the battery properly load tested & if not OK replace with a good 100Ah battery. OE are excellent and last a very long time. These cars are very voltage dependent. If nothing improves then get hold of an OBDII scanner & scan for stored codes. Plug under cover in lower dash below steering wheel/column. Their must be stored codes or you would not get a CEL light. Alternatively get the car scanned with a Star at a dealer. It takes a lot of guessing out of things. It could be a CPS, low fuel pressure, MAF, on plug coil, Temp sensor etc. etc. etc.

Just one thing on the M272 engine. Make quite sure that the airbox is clipped down firmly over the MAF at the rear of the V of the engine. If it leaks air there it can cause strange running & is frequently a really dumb cause of issues.

Good luck!

DC Ross

Thanks for the reply. I got the battery tested and it was toast. I replaced it with a good one like you recommended.

The car started after some prodding, a bit rough, but smoothed out after a few seconds. Shifted into reverse, and it started running really rough, and the Check Engine light went on.
Any suggestions?

Thanks again

gixxerboy

i would pull codes and see what they are related to

Glyn M Ruck

Yep! Pull codes & check that airbox.