2004 Mercedes-benz Sl-class
The Verdict
The 2004 Mercedes-benz Sl-class has 55 owner complaints filed with NHTSA. The most reported issues are body (20 complaints) and brakes (14 complaints). With a Klunk Score of 86/100, it earns a "Smooth Ride" rating. If you're shopping for a Mercedes-benz Sl-class, consider the 2016 model year which has 98% fewer complaints.
Safe Bet
The 2016 has 98% fewer complaints
View the 2016 Mercedes-benz Sl-class dashboard →
Klunk Score: Smooth Ride
This vehicle year has significantly fewer complaints than average. A reliable choice.
How is this calculated?
The Klunk Score ranks this vehicle year against all others in our database based on total owner complaints filed with NHTSA. 100 = fewest complaints (top tier), 0 = most complained-about. Scores above 60 are better than average; below 40 means more problems than most.
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Under the Hood
Each number is a complaint. Darker = bigger problem.
By Category
By Severity
Worst Problems
Complaints
Question 1: The Sensotronic Brake Control (SBC) unit, which is a high-pressure "brake-by-wire" hydraulic system. Component A7/3. The component is currently installed in the vehicle and is available for inspection. Question 2: The vehicle experienced a sudden, catastrophic loss of hydraulic brake pressure while in operation. This failure required extreme physical force on the pedal and significant increase in stopping distance. The vehicle is currently in my garage with chocked wheels until I figure out what's next. A couple days ago, I had the car at a dealer and requested a review of this system and they released the car back to me stating the system status was, "OK" despite me stating to the dealer that the safety-monitoring counter was found to be at 0 on a 63,000-mile car. In all of my research, I believe this "silenced" the vehicle's ability to provide a timely service warning (Code C249F) before total hydraulic failure occurred. Question 3: Mercedes-Benz of Denver performed a diagnostic on January 21, 2026. While the dealer initially claimed the system was "OK," the total failure occurred within 72 hours of their inspection. The reason it was at Benz of Denver is because my independent mechanic confirmed the 0 actuation count which was suspicious to me. I wanted to understand the mechanical integrity of the newly purchased vehicle. Question 4: Yes, inspected by an authorized Mercedes-Benz dealership technician on January 21, 2026. Question 5: To my knowledge there were no mechanical symptoms prior to the red screen however, I cannot confirm or deny that as I had driven less than 1000 miles since I purchased the vehicle. I have no concept of how the braking "should have" felt. The only "symptom" was the technical data anomaly (the 0 actuation count) flagged by an independent shop, which I can attest the dealer refused to investigate fully. On January 24th, 2026, the RED dashboard warning appeared: "Reduced Brake Effect - Start Engine!".
The safety component that is covered under the SBC warranty is the entire brake master cylinder specifically the part that is bad is the brake pedal position sensor The car is undriveable without it, they have a 25-year warranty on it yet they have no parts and no way to fix it which is obviously unacceptable they've also refused to provide a loaner car until they come up with a way to fix my car leaving me on the side of the road with nothing to drive it's unacceptable! My safety and everybody's safety on the road is affected by this because the car won't stop if you drive it and you have really strong legs you can get it to slow down and eventually stop it's completely unsafe The brake pedal cannot tell the computer where it is in its travel which means the system doesn't know that you're applying the brakes which don't work. Yes the problem has been confirmed by two shops one of which has a snap-on scanner which I can attach the scan to showing the issue and currently the car is sitting at a shop that uses Mercedes-Benz only star system the same system that they use in the dealership there is no question at any level what is wrong with the vehicle. The car is not safe to drive to the dealership and now in the winter this $132,000 convertible isn't going to be driven in the salt just to get to a dealership to find out what they're not going to do for me I've already confirmed and share the scans and images and everybody I've spoken with at the dealerships agrees that it's ridiculous that Mercedes has a 25-year warranty on a part that they do not make do not have and cannot fix Yes there are two different brake malfunction lights that are on the dash you cannot clear them as though in a code way like you can on some things and the car is not to be driven, the problem first arose a couple months ago and we started diagnosing it until on the Facebook forum somebody told me that it's covered by a 25-year SBC warranty which when I contacted the dealer and Mercedes-
Mercedes SL600 BCM has electrical issues leading to a fire it is available for inspection. The car can burn down in a garage putting me and all others in or near the dwelling at risk. Yes the problem has been confirmed independently. No BCM issues lead to red light on dash.
The 2003-2006 R230 series seem to have a problem with the BCM (Battery Control Module) as start an electrical fire in the trunk. Very common issue and a safety hazard - this is what happened with my car. Vehicle has dual battery, starter in front, convenience battery in trunk and fuses that operate at 130 Amps - the BCM capacitors and circuit board age and at some point can no longer handle the high current and catch fire.
On many 2003 and 2004 models. Broken fuel tank baffle inside fuel tank. This is well documented and could possibly cause explosion.
ON JULY 22, 2020 THE VEHICLE (2004 MERCEDES-BENZ SL500 (R230)BEGAN MAKING A LOUD BANGING NOISE IN THE REAR WHEN STOPPING AND TURNING. I DELIVERED THE VEHICLE TO A LOCAL SHOP WHERE THE VEHICLE WAS DIAGNOSED AS HAVING A BROKEN BAFFLE IN THE FUEL TANK. THE ONLY SOLUTION IS TO REPLACE THE ENTIRE FUEL TANK. MANY OTHER OWNERS OF THIS MODEL HAVE EXPERIENCED THE SAME ISSUE AND IS CLEARLY A MANUFACTURER DEFECT; THIS CANNOT BE CAUSED BY EXCESS WEAR ON THE VEHICLE. BECAUSE THERE IS NOW A LARGE SECTION OF THE FUEL TANK FREELY SWINGING INSIDE, THERE IS A CHANCE THAT THIS COULD CAUSE A SPARK AND SUBSEQUENT EXPLOSION. I CANNOT SAFELY DRIVE THIS VEHICLE UNTIL THE FUEL TANK IS REPLACED AT A VERY LARGE COST. THIS MODEL SHOULD HAVE BEEN RECALLED WHEN THIS ISSUE WAS FIRST COMING TO LIGHT OVER 15 YEARS AGO.
TL* THE CONTACT OWNS A 2004 MERCEDES-BENZ SL500. THE CONTACT STATED ON VARIOUS OCCASIONS WHILE HIS VEHICLE WAS STATIONERY AND IN PARK, EITHER THE RIGHT SIDE OR THE LEFT SIDE OF THE VEHICLE WOULD RAISE UP THEN DESCEND TO GROUND OVER A THIRTY SECOND PERIOD INDEPENDENTLY WITHOUT WARNING. THE CONTACT ALSO STATED THAT THE HYDRAULIC FLUID LEAKED OUT OF THE ENGINE. THE VEHICLE HAD YET TO BE TAKEN TO A DEALER TO BE DIAGNOSED OR SERVICED FOR THE FAILURE. UPON INVESTIGATION, THE CONTACT LINKED HIS FAILURE TO NHTSA CAMPAIGN NUMBER :08V405000 (SUSPENSION) HOWEVER, THE VIN WAS NOT INCLUDED IN THE RECALL. THE MANUFACTURER HAD YET TO BE NOTIFIED OF THE FAILURE. THE VEHICLE HAD YET TO BE REPAIRED. THE FAILURE MILEAGE WAS APPROXIMATELY 92,000.
I EXPERIENCE A STRONG ODOR OF FUEL WHEN ENTERING MY VEHICLE AND WHEN DRIVING THE VEHICLE, ALSO WHEN DRIVING THE VEHICLE I HEART A LOUD THUMPING SOUND COMING FROM THE TRUNK AREA. SOUNDS TO ME AS THOUGH SOMETHING IS FLOATING INSIDE GAS TANK. THIS ODOR HAS SICKENED ME AND HAS SEVERELY UPSET MY STOMACH TO THE POINT THAT I'M UNABLE TO DRIVE MY VEHICLE EXCEPT FOR A SHORT DISTANCE. THE THUMPING SOUND IS CREATED WHEN VEHICLE IS MOVING OR COMING TO A STOP BUT HAPPENS CONTINUOUSLY WHILE DRIVING. *TR
THE VEHICLE HAS A BRACKET ON TOP OF THE GAS TANK THAT COMES DISENGADED AND CAUSES THIS DISTINCTIVE NOISE WHICH SOUNDS LIKE SOMETHING SWINGING AND TAPPING AGAINST THE GAS TANK AND I HAS TO HAPPEN A LOT DUE TO EVERY SERVICE I HAVE BEEN ASKED ABOUT THE PROBLEM. IT ALSO HAS TO BE SOMETHING WITH MULTIPLE VEHICLES DUE TO ONLINE MERCEDES OWNERS ARE HAVING THE SAME PROBLEM. THE SOUND IS REALLY DISTURBING AND I WOULD LIKE AN ANSWER AS TO WHAT TO DO. THANKS [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6).' *PM
THE VEHICLE HAS 70000 MILES AND ON JANUARY 10, 2019 I WAS APPROACHING A STOP LIGHT AND SUDDENLY WITH NO WARNING (UNTIL AFTER THE FACT ) HAD NO BRAKES, FORTUNATELY I WAS ABLE TO ACCELERATE THROUGH THE LIGHT IMMEDIATELY AFTER BRAKE WARNING LIGHT AND BEEPING. I WAS ABLE TO STOP THE VEHICLE ON THE ROADSIDE. CODES INDICATED FAILED SBC.
I SUBMITTED VIA FAX EARLIER THIS WEEK A FORMAL LETTER TO MR. EXLER THE PRESIDENT & CEO OF MBUSA AND, CC'D MR. KING OF THE NHTSA THAT INCLUDED INFORMATION ABOUT KNOWN CRITICAL SAFETY ISSUED THESE VEHICLES HAD PRIOR TO MBUSA IMPORTING THEM TO THE UNITED STATES. MBUSA FAILED TO DISCLOSE THESE KNOWN ISSUES AND, CHOSE TO IMPORTATION THESE VEHICLES VIOLATING VEHICLE IMPORTATION RULES. YESTERDAY-JANUARY 31, 2019 I RECEIVED A CALL FROM A REPRESENTATIVE OF MBUSA STATING HE WAS CALLING ON BEHALF OF MR. EXLERS OFFICE CONCERNING MY LETTER. I WILL NOT BE INTIMIDATED BY MBUSA WHILE SEEKING THE TRUTH ON WHY MBUSA ALLOWED THESE VEHICLES TO ENTER THE USA KNOWING THESE CRITICAL SAFETY ISSUES EXISTED WHILE MISLEADING CONSUMERS AND, THE NHTSA. ON JANUARY 21, 2019 MY VEHICLE HAD WHAT IS DESCRIBED BY MBUSA AS A CATASTROPHIC FAILURE WHEN THE ENTIRE BRAKE SYSTEM FAILED. THIS FAILURE COULD HAVE KILLED ME - AND, OTHER MOTORIST. MBUSA HAS REPLACED THE SBC UNIT AT LEAST 6 TIMES AND, STILL THE ISSUE AND, OTHER PERSIST. THE VEHICLE HAS BEEN DRIVEN ON AVERAGE 4,000 MILES ANNUALLY. HOW MANY FAILURES MUST HAPPEN BEFORE MBUSA IS FULLY INVESTIGATED? THEY REFUSED TO PROVIDE ME ANY INFORMATION ON THE VEHICLES EXCEPT THE 4 YEAR WARRANTY PERIOD. ONCE I COMPLETE MY RESEARCH ON THESE VEHICLES I WILL SUBMIT MY FINDINGS TO THE NHTSA & MS. KING
TL* THE CONTACT OWNS A 2004 MERCEDES-BENZ SL500. WHEN THE VEHICLE WAS STARTED, THE CONTACT HEARD AN ABNORMAL KNOCKING SOUND UNDERNEATH THE VEHICLE NEAR THE FUEL TANK. ADDITIONALLY, THERE WAS A CONSTANT FUEL ODOR INSIDE THE VEHICLE. THE VEHICLE WAS TAKEN TO MERCEDES-BENZ OF VIRGINIA BEACH (LOCATED AT 4949 VIRGINIA BEACH BLVD, VIRGINIA BEACH, VA 23462, (757) 499-3771) WHERE IT WAS DIAGNOSED THAT ONE OF THE BAFFLES IN THE FUEL TANK FRACTURED, SEPARATED, AND NEEDED TO BE REPLACED. THE VEHICLE WAS NOT REPAIRED. THE MANUFACTURER WAS NOT NOTIFIED. THE APPROXIMATE FAILURE MILEAGE WAS 144,000. THE VIN WAS NOT AVAILABLE.
NOV 14 EARLY MORNING A FIRE STARTED IN THE TRUCK OF MY CAR. COMPLETELY DESTROYED THE CAR. WAS PARKED IN MY GARAGE. TRUCK WAS EMPTY. HAD JUST USED CAR MORNING OF NOV 13 AND ALL WAS FINE. *****PLEASE SEE IMAGES IMG_1733, IMG_1734 AND IMG_1738 THANK YOU.
DUE TO DETERIORATION OF THE WIRING HARNESS CONNECTION OR FAILURE OF THE HYDRAULIC PUMP, THE SENSOTRONIC BRAKE CONTROL (SBC) SYSTEM MAY DEFAULT TO THE HYDRAULIC BACK-UP MODE. IN THE BACK-UP MODE, THE DRIVER HAS BRAKING POWER SUFFICIENT TO STOP THE VEHICLE, BUT GREATER BRAKE PEDAL PRESSURE IS REQUIRED AND BRAKE PEDAL TRAVEL WILL BE NOTICEABLY LONGER. DEALERS WILL INSTALL A BRACKET AND REPLACEMENT GROUND WIRE TO THE SBC PUMP UNIT ON ALL AFFECTED VEHICLES. ADDITIONALLY, DEALERS WILL INSPECT AND REPLACE THE SSC PUMP UNIT IN CERTAIN SL MODELS. THE MERCEDES-BENZ RECALL NUMBERS ARE 2005070007 AND 2005110001. RESEARCH SHOWS ONLY 59% OF THE 100% REQUIRED RECALL WAS DONE PROPERLY BY AN AUTHORIZED DEALER. THIS ISSUE WAS NOT DISCLOSED WHEN I PURCHASED THIS CAR AND, THE REQUIRED WORK WAS NOT DONE AND, MERCEDES SAID THE 60 DAYS FROM RECALL HAD PASSED - YET THE REPORTS SENT TO NHTSA BY MERCEDES BENZ APPEARS TO BE FALSE DATA - THIS SHOULD BE INVESTIGATED.
I PURCHASED THIS VEHICLE IN 2014. MY BRAKES COMPLETELY WENT OUT WHILE DRIVING JANUARY 1 2018. I WAS ATTEMPTING TO STOP AT AN INTERSECTION WHEN THE THE VEHICLE WOULD NOT STOP WITH ONCOMING TRAFFIC ON BOTH SIDES COMING TOWARDS ME. I IMMEDIATELY PRESSED THE ACCELERATOR AND SPED THROUGH THE INTERSECTION TO AVOID AN ACCIDENT....ABSOLUTELY TERRIFYING AND WITHOUT ANY WARNING WHATSOEVER. BECAUSE THE DEALERSHIP WAS CLOSED I WAS UNABLE TO SEEK SERVICE THAT DAY. I CALLED MERCEDES OF RICHMOND VA BEING THAT WAS THE CLOSEST DEALERSHIP WHERE I WAS VISITING AT AT THE TIME. UNFORTUNATELY I COULD NOT GET AN APPOINTMENT UNTIL JANUARY 3RD. I HAD IT TOWED THAT MORNING AND THEY CAME BACK HOURS LATER NOTIFYING ME IT WAS IN FACE THE SBC SYSTEM WHICH NEEDED TO BE REPLACED AT THE COST OF $2006. I WAS OUTRAGED LEARNING THAT MBUSA KNEW OF THIS ISSUE NHTSA CAMPAIGN NUMBER 04V296000 IN JUNE 2004 BUT CLOSED IT OUT IN DECEMBER 2013. I DID NOT PURCHASE THE VEHICLE UNTIL 2014. I ASKED IF THERE WAS ANYTHING THEY COULD DO TO ASSIST ME AS ONE OF THE ASSOCIATES INFORMED ME ABOUT "GOOD WILL" SERVICE WHERE THEY MIGHT CONSIDER MY SITUATION AND HELP. I WAS AGAIN EXTREMELY DISAPPOINTED TO LEARN THEY WOULD ONLY ASSIST WITH $300 AS WE HAVE 2 MERCEDES AND HAVE INCURRED THOUSANDS OF DOLLARS IN KNOWN REPAIR ISSUES OF THE FEW YEARS. I AM ASKING THAT MBUSA ACCEPT THE COST OF THIS REPAIR AS IT WAS A KNOWN ISSUE THAT THEY WERE REPLACING AT NO COST TO OWNER. I HAVE 131,000 MILES ON THE CAR WHICH IS UNDER MILEAGE FOR THAT YEAR. THEY TOLD ME TO ASK MERCEDES IF THEY WOULD CONSIDER ASSISTING IN ANY WAY BUT THEY SAID THERE WAS NOTHING THEY COULD DO.
TL* THE CONTACT OWNS A 2004 MERCEDES-BENZ SL500. THE CONTACT STATED THAT THE SUSPENSION FAILED AND CAUSED THE WHEELS TO DROP AGAINST THE INSIDE OF THE FENDERS. THE VEHICLE WAS INOPERABLE UNLESS LIFTED UP WITH SOME SORT OF LIFTING EQUIPMENT. THE CONTACT INFORMED MERCEDES-BENZ OF OKLAHOMA CITY WHO STATED THAT THE FAILURE WAS A DESIGN ISSUE. THE MANUFACTURER WAS MADE AWARE OF THE FAILURE AND REFERRED THE CONTACT TO THE DEALER. THE APPROXIMATE FAILURE MILEAGE WAS 81,000.
"TAKATA RECALL" 1. THE TOTAL BODY OF MY 2004 SL MERCEDES BENZ SUDDENLY COLLAPSED WITHOUT WARNING TO WITHIN 3 INCHES FROM HI-WAY WHILE TRAVELING ON THE FREEWAY APPROXIMATELY 50 MILES AN HOUR CAUSING ME TO LOOSE CONTROL DUE TO THE WHEELS TO DRAG AGAINST THE UNDERCARRIAGE AND DAMAGE TO FRONT BUMPER PREVENTING ME ME TO STEER FREELY WHILE FLUID FROM THE RUPTURED ABC VALVE LINE APPARENT SPRAYED ON TO THE ENGINE. THE RED ABC LIGHT CAME ON SAYING STOP TO LOW TO DRIVE FOLLOWED BY RED SRS LIGHT (SAFETY RESTRAINT SYSTEM/ AIR BAGS) THE INTERNET REVILES A MULTITUDE OF OWNERS OF THIS CLASS AND YEAR MERCEDES BENZ HAVING THE SAME PROBLEM DUE TO A RUPTURED HYDRAULIC LINE
"TAKATA RECALL" 1. THE TOTAL BODY OF MY 2004 SL MERCEDES BENZ SUDDENLY COLLAPSED WITHOUT WARNING TO WITHIN 3 INCHES FROM HI-WAY WHILE TRAVELING APPROXIMATELY 50 MILES AN HOUR CAUSING THE WHEELS TO DRAG AGAINST THE UNDERCARRIAGE AND DAMAGE TO FRONT BUMPER PREVENTING ME ME TO STEER FREELY WHILE FLUID FROM THE RUPTURED ABC VALVE LINE APPARENT SPRAYED ON TO THE ENGINE. THE RED ABC LIGHT CAME ON SAYING STOP TO LOW TO DRIVE FOLLOWED BY RED SRS LIGHT (SAFETY RESTAINT SYATEM/ AIR BAGS)
I LIVE IN TEXAS AND MY MERCEDES WENT INTO LIMP MODE AT A RED LIGHT. I CAN NOT GET MY TRANSMISSION REPAIRED ANYWHERE ELSE BECAUSE THEY HAVE MADE IT IMPOSSIBLE FOR ANY OTHER SHOPS TO BE ABLE TO SERVICE THIS SPECIFIC TRANSMISSION. THEY TELL ME AND I QUOTE "WE ARE UNABLE TO WORK ON THIS TRANSMISSION BECAUSE IT REQUIRES SPECIAL TOOLS WHICH ONLY MERCEDES DEALERSHIP CARRY SO YOU WILL HAVE TO TAKE IT TO THEM, SORRY" PLEASE, PLEASE, PLEASE RECALL THIS TRANSMISSION!!! ANOTHER TIME I WAS DIVING DOWN THE HWY DOING 70MPH WHEN THE ABC TOO LOW DASH LIGHT CAME ON AS WELL AS MY CAR DROPPING 2 INCHED TO THE GROUND AS I WAS DRIVE 70MPH PLUS I LOST CONTROL OF STEERING. AND ONCE AGAIN NO ONE COULD WORK ON IT BECAUSE IT REQUIRES SPECIAL TOOLS. AND THE ONE PLACE THAT COULD SAID THEY WERE MERCEDES BENZ CERTIFIED. AFTER HAVING MY CAR 3 DAYS AND PAYING $125 FOR A DIAGNOSTIC TEST. I WAS TOLD IT WAS GOING TO BE $5000+ TO FIX. LONG STORY SHORT I PAYED THE CAR LOT WHERE I BOUGHT IT FROM $3587.00 TO FIX IT .
BRAKES FAIL...WARNING LIGHT ONLY AFTER YOU HAVE NO BRAKES...A SUICIDE MACHINE IN TRAFFIC
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