Home · 2012 Mercedes-benz S-class Phev · Complaints

What 14 owners told NHTSA about the 2012 Mercedes-benz S-class Phev

These are the actual owner complaints behind this car’s reliability verdict, filed with the federal government, unedited. They’re unverified reports, not confirmed defects: read them as leads for your pre-purchase inspection, not a diagnosis.

All (14)Crash / fire / injury (2)Engine (7)Fuel system (5)Transmission & drivetrain (3)Electrical system (2)Speed control (2)Electronic Stability Control (esc) (1)Steering (1)

2 of 14 complaints match · Electrical system · clear filters

Aug 26, 2024Electrical systemEngineFuel system

I purchased this vehicle in July 2020. I did a through check for recalls, warranty problems and could not identify any with this vehicle. From the get go the check engine light would come on. I checked the codes and they indicated an "electrical fault on bank 1, oxygen sensor 1. I replaced the wiring harness on that sensor as well as the sensor. From then until now the car would code weekly about the same issue. Eventually I started using a catalytic converter cleaner (it cleans off sulfur deposits) in an attempt to solve the issue. It would work for a couple of tanks of gas and then continuing coding. I asked MB on numerous occasions about what the issue was. They all said they had no idea. It looks to me like they knew what the issue was, but kept it to themselves. Several weeks ago I received a letter in the mail(not dated by postmark) but the letter was dated August, 2023. The letter outlined an issue with the catalytic converter system identifying my vehicle by vin. The same problem I have had all along. The letter came at a time when the car codes almost daily with the same issue as always, ONLY NOW THE VEHICLE STALLS occasionally while waiting at stop lights. I said great. I called to get an appointment to fix the issue only to be told that the fix window had passed. I told them that I just got the letter. They told me that the fix expired in December 2023. I called MB hotline at 1-800-367-6372 to see what was up. They said they would get back to me in 3 days. It's been a week so I called again and they advised me they can't help. It's an issue for the 2011, 2012, 2013, and 2014 MB S550 W221. Why is this not a recall and why won't they fix it. It's an expensive repair. They sent me the letter and said it was expired 6 months before I received the letter. Can you help?

NHTSA ODI 11610863

Jan 8, 2019Electrical systemElectronic Stability Control (esc)Engine

VEHICLE STALLS INTERMITTENTLY IN TRAFFIC, INTERSECTIONS. VEHICLE STARTS INTERMITTENTLY, RUN, OPERATES HOWEVER, STALLS WHEN TRANSITIONING FROM STOPPED POSITION TO ACCELERATION. A KNOWN DEFECT PURSUANT TO MERCEDES BENZ SERVICE CAMPAIGN 2012080004. PRESENTED VEHICLE TO MERCEDES BENZ FOR REPAIR. THEY CONFIRMED THAT THE VEHICLE WAS EXPERIENCING THE PROBLEMS DESCRIBED IN THE CAMPAIGN AND REQUIRED THE REPLACEMENT POWER ELECTRONICS MODULE HOWEVER, THEY REFUSED TO COVER THE REPAIR OF THE VEHICLE AND PRESENTED ME AN $11K ESTIMATE FOR REPAIR. MERCEDES BENZ MANUFACTURER REFUSING TO HONOR KNOWN DEFECT RECALL. EXTREME BAD FAITH.

NHTSA ODI 11165146

Working with the data? Download all 14 complaints as CSV · fetched from NHTSA July 21, 2026

How to use these: a complaint is one owner’s report, filed voluntarily and published unverified. Patterns matter more than any single story. If several owners describe the same failure at similar mileage, put that system at the top of your pre-purchase inspection list. Back to the full 2012 Mercedes-benz S-class Phev verdict →