There are 3 owner-reported electrical system complaints for the 2009 Mercedes-Benz SL-Classin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
I'm reporting a SERIOUS SAFETY ISSUE affecting all Mercedes-Benz R230 series SL roadsters, model years 2003–2012, of which approximately 85,000 were sold in the United States: • There are numerous reports on R230 SL owners' online forums that an electrical device located in the trunk of these vehicles known as the BCM [Battery Control Module] is prone to CATASTROPHIC FAILURE and melt-down. • The failed BCM can subsequently CATCH FIRE – potentially destroying the vehicle and endangering lives and property nearby. See photos attached from one SL owner's experience. • MBUSA, its dealers, many SL owners, independent service centers and salvage yards are aware of this problem: multiple reports detailing it can easily be found on the Internet. Possible modifications to alleviate the danger have been affected by some SL owners, one picture of which has been uploaded here. • Mercedes-Benz is surely aware of the issue but has not recalled nor issued TSBs associated with this serious problem, nor has MBUSA acknowledged that vehicles modifications to alleviate the risk of failure and subsequent fires have been developed by owners and mechanics. • No symptoms are known to appear prior to melt-down, other than odors and/or smoke emanating from the SL's trunk. By then, it is TOO LATE. I respectfully request NHTSA open an investigation into this issue and require Mercedes-Benz address it by affecting modification or replacements of the faulty BCM system components in R230 vehicles.
This particular model 2009 Mercedes SL 550 hardtop convertible 5.5 liter motor has two batteries and accessory battery that battery that’s located in the trunk in the main starting battery that’s on the firewall. These batteries are both new in OEM recommended. If the car sits for 24 hours, it will not start. The electrical system is completely drained. There are many forms describing the same issue but yet the SL model is not included in a civil lawsuit. Mercedes-Benz definitely knows they have an issue in somehow it needs to be rectified.
TL* THE CONTACT OWNS A 2009 MERCEDES BENZ SL550. WHILE TRYING TO EXIT THE VEHICLE, THE DOOR HANDLE FRACTURED AND ALL OF THE DOORS AUTOMATICALLY LOCKED PREVENTING THE CONTACT FROM EXITING THE VEHICLE. THE VEHICLE WAS TAKEN TO A DEALER. THE TECHNICIAN DIAGNOSED THAT THE COMPUTER'S THEFT SYSTEM ENGAGED ONCE THE DOOR HANDLE FRACTURED AND NEEDED TO BE REPROGRAMMED. THE VEHICLE WAS REPAIRED. THE MANUFACTURER WAS MADE AWARE OF THE FAILURE. THE FAILURE MILEAGE WAS 60,000.
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 26, 2026