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: 82,250 mi (16,500 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, 82,456 mi
Engine stopped running on freeway Restarted after 15 minutes stopped again after 5 minutes running.
Ran codes found failure of the speed sensor .R&R part cleared codes all good.
Visitor, 2004 Mercedes-Benz ML500, 16,500 mi
problem started leaving work, motor stalled . pulled over, then engine cranked several times and restarted after a few times. drove about 10 miles to my home. the next day however, drove a few times and vehicle drove fine. after it sat about another 4 hours i needed to go to the pharmacy, so went to start and all that took place was just crank , but no start. a half hour later, it started. i ran inside the house to grab my phone to go and discovered the motor had stalled again. after another 10 min. i checked the fuses, all was well. i then proceeded to trouble shoot. then located the fuel filter located next to the gas tank. tapped a few times, tried to start. it started. i backed out of my driveway to turn vehicle around and backed into the carport. after putting into park the motor stalled before i turned the key to the off position.
Visitor, 2006 Mercedes-Benz ML500, 72,006 mi
car would not start. 2hrs later it started. I took it to Dave's Foreign Car Repair He fixed it for$378.79. Hope it works a while. Seems like I am having a lot of problems. the car has been taking very good care of I bought it new for my wife.
Visitor, 2005 Mercedes-Benz ML500, 88,000 mi
Just purchased, haven't been give. It yet but already they've delayed by a week to sort this issue