My 2014 ML550 (115,000 miles) stalled at a red light today and when I went to restart it would not turn over. Event did not throw any codes. It sounds like the starter is engaging, but I’m not certain. Put a jump box on the battery just to make sure that wasn’t the problem and it made no difference. The car has been having some long starts recently and it did throw a code once for low fuel pressure. I could see this being the reason the car stalled, but it should turn over on subsequent restart. Hoping the engine isn’t seized. Any idea of what could cause this other than internal engine failure?

 

Replace both batteries and report back.

 

I replaced the main battery under passenger seat 2 weeks ago. Do you think the auxiliary battery could cause this?

 

Not sure. On a 9 or 10 year old vehicle, depending on build date, all batteries should be assumed to be kaput.

Safest choice is to replace it and see what happens.

 

Well, my first thought is a seized engine. Get a ratchet on the crank pulley bolt and see if it will turn by hand.

 

Yeah. Symptoms + no codes worry me. I’ll report back on Monday with results (working the weekend). My first plan of action was to try to turn engine over by hand. 🤞

 

Unfortunately these twin turbo V8's are not ageing gracefully. Good luck, let us know...

 

I will check both main (new) and aux battery voltages Monday. Hopefully one of them is the culprit.

 

That’s a fact!!!

 

Any updates on what caused this problem?
Thanks