2012 Mercedes-Benz ML350 Problems

What owners report

Owners of the 2012 ML350 report a mix of stalling and power-loss episodes, fuel smells linked to the diesel/fuel system, and turn signals that quit working after a few minutes of driving. Many complaints involve relatively low mileage for the year, and several describe dealers unable to find a stored fault code or declining repairs once the vehicle was out of warranty.

1. 1
   Engine

   Engine stalls or loses power while stopped or driving

   • 16 complaints (25%)
   • median 19,600 mi at 2.0 yrs old (14 state mileage)
   • 1 mention a crash, fire or injury
   • filed 2012–2025

   Complaints describe the engine quitting at traffic lights, at intersections, or while traveling at speed, sometimes with the vehicle failing to restart. Owners report the vehicle shaking or refusing to accelerate beforehand, and dealers saying no fault code was stored or that the cause could not be found; some had the high-pressure fuel pump replaced without the stalling stopping. Reported from a few hundred miles on nearly new vehicles up through roughly 145,000 miles, with many under 50,000 miles.

   Recall 22V955000

   What to check: Ask for service history covering fuel pump and fuel pump control unit work, and whether recall 22V955000 was performed. Test drive at low speed and at idle in traffic, and check the spare tire well for water.

   2 excerpts from owner complaints in NHTSA records

   “This happened as a new car, only now, after it happened about 5 or 6 times, we came to know this weired and dangerous problem-it loses the power at a stop; at red light, and even when we tried to start to move. When it happened, at first several times, we were thinking maybe I did something, after 5 to 6 times happened to me and to my wife, we just came to understand it is such dangerous problem. …”

   NHTSA complaint #10485224, filed 2012-11, 500 miles

   “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. …”

   NHTSA complaint #10501076, filed 2013-03, 21,200 miles
2. 2
   Electrical system

   Turn signals quit after a few minutes of driving

   • 12 complaints (18%)
   • median 50,000 mi at 6.8 yrs old (7 state mileage, few)
   • 2 mention a crash, fire or injury
   • filed 2013–2024

   Owners describe the indicators stopping work after roughly 5 to 15 minutes on the road, sometimes sooner when a phone is paired over Bluetooth, while the blind spot assist also switches off. Complaints state that restarting the engine brings the signals back briefly before they fail again, and that dealers pointed to the steering column module, cleared a stored code, or quoted a replacement. Mostly reported between about 39,000 and 77,000 miles, in some cases after a few years of ownership.

   What to check: During a long test drive, check the indicators after 15 minutes and with a phone paired; ask whether the steering column module has ever been replaced and keep the invoice.

   2 excerpts from owner complaints in NHTSA records

   “On occasion the blind spot assist becomes inoperative. Frequently when this occurs, it also deactivates the turn signals creating, in my opinion, a very dangerous situation. Each time it's happened in motion on an expressway. I've contacted the local mercedes benz dealer who tells me the only way to correct this problem is to pull over to the side of the road, turn off the car and turn it back on to reactivate the system. Not only is this inconvenient, it doesn't always correct the problem. …”

   NHTSA complaint #11064734, filed 2018-01, 76,900 miles

   “Steering column module is intermittently not working as intended, therefore the blinkers will sometimes not work causing it to be a safety concern if I can not signal where I am going. When looking this issue up online I have seen numerous different forums and posts where people have had the same issue. When I took my vehicle to the dealership they had told me that this is very common with the vehicle I have and they do the fix all of the time, just for the issue to happen yet again later down the road.”

   NHTSA complaint #11602716, filed 2024-07
3. 3
   Fuel system

   Fuel pump or pump control unit failure causing a stall

   • 9 complaints (14%)
   • median 59,383 mi at 3.5 yrs old (5 state mileage, few)
   • filed 2013–2026

   Owners describe the vehicle losing power and stalling with no warning, with diagnosis pointing to the fuel pump or the fuel pump control unit. Several complaints mention water collecting in the spare tire wheel well and damaging the control unit, and note that a recall covering water intrusion into that area exists but that parts or reimbursement were not always available. Reported from about 48,000 up to 141,000 miles, including on highway drives at speed.

   Recall 22V955000

   What to check: Check the spare tire wheel well for standing water or rust, and confirm with a dealer whether recall 22V955000 has been completed on the vehicle.

   2 excerpts from owner complaints in NHTSA records

   “While driving, vehicle stalled. Mechanic found water in spare wheel Well. And fuel module and fuel pump shorted out. Had vehicle repaired; 07/22. The vehicle stalled again in 12/22. Mechanic found water in spare wheel well. Had to replace fuel pump. In February,2023, Mercedes Benz notified me of a recall, NHTSA Recall I D: 22V955 ; water intrusion in the spare wheel well. And, stated their local dealer would repair vehicle or reimburse me for the cost of repair, if I had the repair done already. …”

   NHTSA complaint #11555567, filed 2023-11

   “Vehicle stalled without warning, and I was advised by a mechanic that the fuel pump control unit was reporting a fault through the onboard diagnostics port and the check engine light on the dashboard. It was necessary to replace the fuel pump control unit as the defect was intermittent and subject to occur at any time the vehicle was being driven. There is no available solution save the replacement. I had the fuel pump control unit replaced at my cost and after replacing it found information concerning the NHTSA recall campaign online. …”

   NHTSA complaint #11634404, filed 2025-01
4. 4
   Fuel system

   Strong fuel or diesel smell in the cabin

   • 5 complaints (8%)
   • median 59,383 mi at 6.5 yrs old (5 state mileage, few)
   • 1 mention a crash, fire or injury
   • filed 2015–2022

   Complaints report a strong fuel or burnt-plastic odor inside the cabin while driving, sometimes strong enough that occupants stopped the vehicle for fresh air. Owners describe repeated dealer visits before a leak was traced to the fuel lines, pump, connector or injector area, and in several cases the smell returned after a repair. Reported from about 42,000 to 103,000 miles.

   What to check: Smell inside the cabin and around the engine bay after a drive, and look under the vehicle for fuel or oil drips. Ask whether fuel lines, clamps and the pump area have been inspected.

   2 excerpts from owner complaints in NHTSA records

   “After being into authorized mercedes benz dealership only for an strong diesel fuel smell and oil leak 3 times in less than 4 months on our ML350 bluetec engine fuel smell is strong enough that we have a sever headache ,nauseous feeling and have to stop the car and get out for fresh air, opening windows only gets more of the smell in of fuel and burning plastic. This happens while vehicle is in motion ,both on city streets and on highways, more pronounced when driving.”

   NHTSA complaint #11090864, filed 2018-04, 49,000 miles

   “Took our 2012 Mercedes-Benz ML350 bluetec to the dealership numerous times due to an overpowering fuel smell and burned plastic in the cabin of the vehicle. We had to stop several times because we felt sick as if we were going to pass out and/or throw up. But, then it started to affect our children and we demanded that the dealership find the root cause. They finally determined that it was a fuel leak around the fuel injectors that completely charred components in the fuel injection cavity. …”

   NHTSA complaint #11185111, filed 2019-03, 103,000 miles

Buying note. Have a pre-purchase inspection include the fuel system, the spare tire well for water, and the steering; confirm in writing that recall 22V955000 has been completed and ask for records of steering column module work, since turn signal faults are reported repeatedly.

Summary written with AI from a sample of 60 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.