The engine may develop a stalling and/or no start condition due to a failed crankshaft position sensor.Google+
Car Problem Reports
Mercedes-Benz ML500 Engine Performance Problems Due to Crankshaft Position Sensor Failure
Mercedes-Benz ML500 Problem
Average Mileage: 84,646 mi (40,000 mi - 170,000 mi)
Visitor, 2006 Mercedes-Benz ML500, 85,000 mi
I had same issue with engine stalling after driving fine for a few minutes, up to an hour. I'd park the car, start again to drive, and engine stalls as soon as I am stopped at a light or stop sign. It will only crank but not start after this happens. I called for a tow, and before tow arrived, it restarts (only to stall again after driving about 2 miles) After researching issue, I had my crankshaft position sensor replaced. Happy as can be, drove towards home, only to have car stall AGAIN. However, this time it will restart, but as soon as I try to put it into drive or rev the engine in park, it stalls. Called a mechanic to help pull codes off computer (both times check engine light is illuminated), it says bad crankshaft position sensor. WHAT? So my mechanic drives it to his shop, but before arriving it stalls on him. Sitting at the side of road, he decides to check his work on crankshaft position sensor replacement from yesterday. With engine running he tries to feel for wire/sensor. It stalls as soon as he touches the wire. He restarts car and wiggles the wire again, and low and behold it stalls. Conclusion is that the sensor is probably ok, but the wire connector is bad. He is in the process of repairing wire now because MB wants $900 (yes with eyes wide open and jaw dropping) for the entire engine wire harness since they don't sell just the connector. Will update after repair to verify that was the issue.
Car stalls frequently, usually at intersections of heavy traffic, hard to start. Starts sometimes after 20 to 45 minute cool down. Was diagnosed by Mercedes Road service person, and myself since I had one replaced in my 2002 S450, as a crankshaft sensor. The Mercedes dealer charged $120 to diagnose the problem even though I informed them of the situation. It appears the Crank Shaft Sensor is an ongoing problem across some years and models. The ML also needs a Power Steering Pump, quite expensive. I read on the Web that, for some reason, Mercedes uses "Cheap" motors. I feel a prestigious company like Mercedes, recognize chronic problems and subsidize the repairs in some fair fashion.
Visitor, 2004 Mercedes-Benz ML500, 157,000 mi
replaced crankshaft position a few months ago and now it is happening again.
Visitor, 2003 Mercedes-Benz ML500, 98,045 mi
Crankshaft Position Sensor Failure, $380.00 to repair at dealership
Visitor, 2005 Mercedes-Benz ML500, 74,000 mi
Had to replace crank sensor and fuel pump after vehicle died at intersection. Cost to repair $1250!
Visitor, 2005 Mercedes-Benz ML500, 40,000 mi
Typical symptoms- car stalling.
Visitor, 2004 Mercedes-Benz ML500, 76,000 mi
To begin with, the problem which involves the battery & (we were told)the crankshaft sensor, & later told, was due to corrosion on the battery posts, has not been diagnosed or fixed after two trips to the MB dealership. We were told at the last visit that the next thing they would try would be replacement of the battery casing and of the generic battery for an MB battery at a cost of over $700. We are NOT going to do this. The car has run on good non-MB batteries for 10 years. The battery is not holding a charge. The MB mechanics determined THAT much but found nothing that was drawing off the battery. Not sure this is related but about 7 years ago, the navigation unit stopped working; the radio and CD player soon followed. For the past 4 or 5 yeas the airbag light has been on; the MB mechanics checked the airbags & determined them to be completely functional, but the light comes on whenever we drive the car. The recurrent battery issue is typically heralded by the key not working to open the car door (but not always). The battery can stall when the car is running, when it slows in a parking lot or after it has been parked - for 5 minutes or overnight. It is completely unpredictable - nut once it's dead now, it's dead. We're on our 3rd battery in about as many months. I don't think the MB techs we see have a clue what's at the bottom of this. To me the car is a lemon and I love the ML's. This is my second. The first, a 2000 was 100% reliable.
Visitor, 2006 Mercedes-Benz ML500, 95,000 mi
Car would crank but not start. removed key and it started the second time. Took it to independent mechanic who pulled the code and said it was the crank position sensor. $400 repair incl labor.
Ingine abruptly stalls at intersections....requires couple of restarts to start the engine.