Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2012 Mercedes-Benz ML350 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2012 Mercedes-Benz ML350. The contact stated while driving 40 mph, the check engine warning light was illuminated. The contact pulled over to the side of the road and attempted to restart the vehicle to see if the light would disappear however, the vehicle would not restart. The contact called the local dealer who arrived at the scene and connected the vehicle to a diagnostic machine to clear the sensor code for the vehicle to restart however, the failure persisted. The contact took the vehicle to the local dealer to be diagnosed. The contact was informed that the failure was due to the crankshaft position sensor. The vehicle was not repaired due the cost. The manufacturer was made aware of the failure. The failure mileage was approximately 145,000.
The contact owns a 2012 Mercedes-Benz ML350. The contact stated while driving uphill at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. In addition, the contact stated that the vehicle was shaking abnormally. The contact stated that the abnormal shaking occurred at various speeds. The vehicle was taken to the dealer where it was diagnosed with timing chain failure. The contact was informed that the timing chain needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure but provided no assistance. The contact was advised to contact the NHTSA Hotline to report the failure. The failure mileage was approximately 65,000.
The contact owns a 2012 Mercedes-Benz ML350. The contact stated that after starting the vehicle, the check engine warning light illuminated. The contact stated that the vehicle was towed to a dealer who diagnosed a failure with the camshaft. The contact researched online and found a Technical Service Bulletin regarding the camshaft failure. The dealer advised the contact that the warranty had expired for the camshaft repair. The vehicle had not been repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 96,000.
The contact owns a 2012 Mercedes-Benz ML350. The contact stated while the vehicle was being inspected, the independent mechanic informed him of a diesel and oil leak. The contact stated no warning light was illuminated. The contact towed the vehicle to the local dealer. The vehicle was not diagnosed or repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 110,000.
My name is [redacted] My vehicle cut off on me 3 times twice while stationary and once at an intersection. Found oil in engine control module due to failed cam position sensors. Oil has traveled through the engine harness to ECM causing oil to get into module and cause it to shut down but it did start back up. This is very dangerous and could cause serious injury to someone.
Hello, ref: ML350 camshaft solenoid leak! I am seeking out for your help wrt to a situation with 2012 ML350. Enclosed herewith is an inspection report from a recent service visit requiring close of $8K in repairs for your reference. Engine harness (oil lled harness and various components have oil in them, all components with oil should be replaced, quick insp found a few components but there May be more that need to be replaced) after reviewing the inspection report, I did some research and came across campaign no. 2012070002, September 2012 (copy enclosed for your reference), wherein Mercedes had identified it as a part of recall and service campaign and agrees to cover the cost and labor damages to any downstream components due to the camshaft solenoid leak. …
Driving along at 65mph on highway with cruise control on, 80 degrees, sunny and clear weather the fuel line came loose and engine lost all power. Diesel fuel spilled on vehicle and roadway. Vehicle had 86,432 miles on it at the time. The engine is a 3 liter Mercedes diesel bluetec. Had the vehicle been gas instead of diesel I'm sure it would have caught fire. Car had to be towed. Was told that two fuel line clamps had failed and needed replaced. The car has only been maintained and repaired at Mercedes-Benz dealerships. True to form, Mercedes was no help to reimburse the cost of repairs. Total repair costs without tow was $321.88. Tow was paid by their roadside assistance program. Please investigate this safety issue.
My wife was driving my ML350 on the freeway with my 7 year old son in the back. She said the vehicle started to shake in an unusual way so she decided to get off at the nearest exit and when she applied the brakes on the off ramp the car's engine stopped. Engine light came on, dash read inoperable yet all the electrical was still on. She tried to turn the key and restart it but the car would not start. Before this incident we had not experienced any problems. This is a 2012 model with just over 21,000 miles and was just serviced two weeks prior to the incident . It happened all of a sudden. The car was hit by another vehicle- rear ended with both my wife and son still in it.
Tl* the contact owns a 2012 Mercedes-Benz ML350. While at a stop light, the vehicle stalled without warning. In addition, the radio and air conditioner failed to function. The failure recurred numerous times. The vehicle was taken to Mercedes-Benz of coconut creek (4250 sr 7, coconut creek, fl 33073, phone: [phone]) where it was diagnosed that the fuel pump failed, there was a leak in the air conditioning system, and the radiator failed and needed to be replaced. The vehicle was not repaired. The manufacturer was not contacted. The approximate failure mileage was 48,000.
From the day one, during the first 25 minutes of driving, my new 2012 mb ML350 vibrates and make grinding noise just in between 40 to 45 miles per hour steady driving. After about 30 minutes of driving, the vibration and the noise are not noticeable. Mb and the dealer were trying to fix the problem but failed to resolved the problem. Now, they have concluded that the vibration is normal and is characteristic of the car. Any problems mb can't solve is normal!! What kind of car is it that vibrates for first 25 minutes of driving at certain speed is normal!!
Engine complaints in other ML350 years
Frequently asked questions
How common are engine problems on the 2012 Mercedes-Benz ML350?
NHTSA has 23 complaints about the engine & cooling of the 2012 Mercedes-Benz ML350, 35% of the model year's 65 complaints. The component named most often is engine › crank/camshaft position sensor (1 mentions).
Is there a recall for 2012 Mercedes-Benz ML350 engine problems?
No. NHTSA lists no engine & cooling recall for the 2012 Mercedes-Benz ML350, though it has 3 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2012 Mercedes-Benz ML350 engine problems start?
Half of the complaints with a recorded mileage happened before about 43,000 miles, and 47% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 0 fires and 0 injuries to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.