2008 Mercedes Benz S550

I’m reporting a serious safety issue with the balance shaft sprocket in my Mercedes-Benz S550 (M273 engine, 273.968). This is a known defect that causes the sprocket to wear out far too early due to poor material design. When it wears, it throws off the engine timing, leading to check engine lights, rough idling, reduced power, and even stalling. In some cases, the engine can shut down while driving, which is a major safety risk. Thousands of people have experienced this exact problem, and it’s all over Mercedes forums, Reddit, and technical bulletins. Mercedes quietly updated the part in later models, which shows they knew the early ones were defective. Some people got repairs under warranty or “goodwill,” but most of us are stuck with thousands in repair bills for something that clearly shouldn’t have failed. This isn’t just a mechanical issue—it’s a safety concern. Imagine merging onto a highway or turning through an intersection when the engine loses power. That’s a real risk with this defect. Mercedes should be held accountable, and NHTSA needs to investigate and push for a recall before someone gets hurt or worse.

The contact owns a 2008 Mercedes-Benz S550. The contact stated while driving 40-50 MPH, the vehicle was shuddering intermittently. The contact stated that the failure recurred while at a complete stop. The check engine warning light was illuminated. The contact stated that the failure had been recurring intermittently. The vehicle was taken to an independent mechanic, where it was diagnosed that the wiring harness was causing an engine misfire. The mechanic related the failure to an unknown recall. The dealer was notified of the failure. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 40,000.

We were traveling home and our TPMS indicated a tire failure. The PSI starting dropping rapidly. We took the tire off and found that only 4 " of rubber holding the back sidewall together on the tire. I then inspected the other tires on the car (which were purchased and installed at the same time) are showing signs of failure as well. All of the tires are 255-40-r19 We had a family of 4 in the vehicle at the time of the incident.

The contact owns a 2008 Mercedes-Benz S550. The contact stated while driving 35-40 MPH, the message "SAFETY" was temporarily displayed on the instrument panel. Additionally, the contact stated while starting the vehicle on several occasions, the message " SAFETY " was displayed on the infotainment system screen. The check engine warning light was illuminated, and the messages "Active Head Lamp Inoperative" and "Service Required. Do Not Shift Gears" were displayed. The contact also stated that upon shifting into drive (D), the gear shift indicator displayed that the transmission was in park (P). The contact stated that the vehicle failed to shift into the intended gear and had become undrivable. An independent mechanic replaced the battery; however, the failure persisted. The mechanic informed the contact that the computer needed to be reset. The vehicle was not repaired. The used car dealer was notified of the failure. The Mercedes-Benz dealer and manufacturer were not notified of the failure. The failure mileage was approximately 176,310.

TL* THE CONTACT OWNS A 2008 MERCEDES-BENZ S550. THE CONTACT STATED THAT WHILE STOPPED, THE VEHICLE WAS SUDDENLY REAR-ENDED CAUSING THE VEHICLE'S DRIVER AND PASSENGER FRONT SEAT HEAD REST AIR BAGS TO DEPLOY. THE CONTACT STATED THAT HE SUSTAINED BROKEN BONES IN HIS NECK AS WELL AS INJURIES TO HIS LEFT ELBOW AND BACK AREA. THE FRONT PASSENGER RECEIVED INJURIES TO HIS NECK AND BACK AREA AND WAS TRANSPORTED THE HOSPITAL BY AMBULANCE WHILE THE DRIVER DROVE HIS VEHICLE TO THE HOSPITAL. A POLICE REPORT WAS FILED. THE VEHICLE WAS TAKEN TO A LOCAL A BODY SHOP POST INCIDENT WHO REPAIRED THE BUMPER AMONGST OTHER PARTS OF THE REAR OF THE VEHICLE. THE VEHICLE WAS THEN TOWED TO THE DEALER (MERCEDES-BENZ OF WAPPINGERS FALLS (134 OLD POST RD, WAPPINGERS FALLS, NY 12590 PHONE: (845) 298-0600) WHO PERFORMED THE HEAD REST AIR BAGS REPLACEMENT, AS WELL AS, ELECTRICAL AND OTHER REPAIRS DUE TO THE COLLISION. THE MANUFACTURER WAS MADE AWARE AND OPENED A CASE REGARDING THE MATTER. THE CONTACT WAS CONCERNED WITH THE FORCE OF THE HEAD REST AIR BAGS DEPLOYMENT. THE APPROXIMATE FAILURE MILEAGE WAS 78,013. *DR*JB

P-RC-200808004 BODY CONTROL ACCELERATION SENSORS...MODELS 2001-2008 11/4/2008 - 200807001 RE-CODE THE SOFTWARE CALIBRATION NUMBER (SCN) 11/04/2008 - 200803005 REPLACE FRONT SAM S-SC-2012070002 RETROFIT ADAPTER WIRING HARNESS ON CAMSHAFT ADUSTMENT SOLENOIDS MODELS 2005-2011 S-RC-200807001 REVISION TO STEP Z, IN WORK PROCEDURE RECODE THE SOFTWARE CALIBRATION NUMBER (SCN). *TR

EVEN CHANGE TO NEW TIRES, THE AIR PRESSURE UP TO 37 AND ALWAYS AFTER 1 WEEK OR SO, DOWN TO 33, COMPLAIN AND CHANGE TIRE AND STILL HAVE THE SAME RESULT. YOU COULD ONLY CHECK THE TIRE PRESSURE AFTER YOU RUN FOR A WHILE. MASSAGE CHAIR, AFTER OPERATION AND ALL THE SUDDEN IT STOP. CLOCK IN THE CABIN DOESN'T CHANGE EVEN YOU SET IT UP AND THE INTERNAL SAID THE RIGHT TIME AND THE FRONT DOESN'T CHANGE

MY VEHICLE HAS A STRONG GAS ODOR WHILE DRIVING BUT PARTICULARLY WHEN THE VEHICLE IS STATIC OR PARKED. THIS SMELL IS SO STRONG THAT I CANNOT SIT IN THE CAR AND MY CLOTHES REAK OF THE SMELL. THERE HAS NOT BEEN ANY EXTERNAL GAS LEAKAGE OR PERFORMANCE ISSUES WITH THE CAR. ONLY THE GAS ORDOR THAT HAS GIVEN ME A HEADACHE AND MAKES ME NAUSEATED. THE CAR ONLY HAS 70,000 MILES ON IT.

TL* THE CONTACT OWNS A 2008 MERCEDES BENZ S550. THE CONTACT STATED THAT THE VEHICLE HAD EXPERIENCED AN ABNORMAL FUEL ODOR. THE VEHICLE WAS TAKEN TO THE DEALER WHERE IT WAS DIAGNOSED THAT THE FUEL TANK WAS FRACTURED AND NEEDED TO BE REPLACED. THE VEHICLE WAS NOT REPAIRED DUE TO THE PART BEING ON BACK ORDER. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE. THE CONTACT HAD REFERENCED NHTSA CAMPAIGN: 12V557000(FUEL SYSTEM, GASOLINE) AS A POSSIBLE SOLUTION TO THE FAILURE HOWEVER THE VIN WAS NOT INCLUDED. THE FAILURE MILEAGE WAS APPROXIMATELY 91,000.