The engine may develop a stalling and/or no start condition due to a failed crankshaft position sensor.
Car Problem Reports
Mercedes-Benz ML500 Engine Performance Problems Due to Crankshaft Position Sensor Failure
Mercedes-Benz ML500 Problem
Average Mileage: 86,338 mi (40,000 mi - 170,000 mi)
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, 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.
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.