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…
2009 Mercedes-Benz SL-Class electrical problems
severe 3 complaints filed with NHTSA · avg repair $850 · see electrical across all vehicles →
Complaints
3
Recalls
0
Avg fix
$850
1fire
When does it fail?
Of the 3 electrical complaints filed for the 2009 Mercedes-Benz SL-Class, here's the actual mileage breakdown — failures cluster heaviest at 50,000-75,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
No new NHTSA electrical complaint has been filed on this vehicle in over 3 years — the issue may be aging out of the active population.
What owners are reporting 3 most recent
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…
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…
Had electrical trouble with your 2009 Mercedes-Benz SL-Class?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the electrical problem on the 2009 Mercedes-Benz SL-Class?
It's a meaningful issue. 3 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $850.
At what mileage does the electrical typically fail?
Based on the 3 complaints filed, electrical issues most often appear around 60,000 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $850 for electrical repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to electrical?
No active recalls currently cover electrical issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2009/Mercedes-Benz/SL-Class.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.