Tl* the contact owns a 2012 Mercedes-benz e550. While attempting to put on the driver's side seat belt, the seat belt fractured. There were also electrical failures in the vehicle. The vehicle was towed to the dealer where it was diagnosed that the seat belt would have to be reprogrammed. The vehicle was repaired. The manufacturer was not made aware of the failure. The approximate failure mileage…
2012 Mercedes-Benz E-Class electrical problems
moderate Owners of the 2012 Mercedes-Benz E-Class have filed 14 NHTSA complaints about the electrical, typically surfacing around 72,000 miles at roughly $850 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See electrical across all vehicles →
Failure mileage
Complaints
14
Recalls
0
Avg fix
$850
| Model year | electrical complaints |
|---|---|
| 2008 E-Class | 15 |
| 2009 E-Class | 5 |
| 2010 E-Class | 12 |
| 2011 E-Class | 7 |
| 2012 E-Class (this page) | 14 |
| 2013 E-Class | 12 |
| 2014 E-Class | 35 |
| 2015 E-Class | 4 |
| 2016 E-Class | 8 |
When does it fail?
Of the 14 electrical complaints filed for the 2012 Mercedes-Benz E-Class, here's the actual mileage breakdown — failures cluster heaviest at 25,000-50,000 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 9 years — the issue may be aging out of the active population.
The failure pattern owners describe
Oil leakage from the cam solenoids into the engine wiring harness is the most common complaint across these 14 narratives. The oil travels through the harness to O2 sensors, oxygen probes, and the DME (engine computer), causing rough running, stalling, and potential complete shutdown while driving—a genuine safety hazard. Owners cite repair costs of $5,000 to $8,000. Mercedes previously recalled this defect on earlier model years but excluded 2012 models despite the identical problem, and dealers now refuse warranty coverage.
Electronic ignition switch failures cause the transmission to suddenly shift into Park at speeds below 10 mph without warning, stopping the vehicle violently. One owner experienced this in the middle of an intersection; another reports the failure repeating immediately after shifting back to Drive. A service bulletin documents the issue, yet Mercedes denies warranty repair on out-of-warranty vehicles.
Backup camera screens go black approximately 50% of the time in Reverse, especially in wet weather—no fault shows on dealer diagnostics. The Distronic Plus adaptive cruise system also drops unexpectedly during low-speed and stop-and-go traffic, nearly causing rear-end collisions. Less common failures include trunk latch wiring defects, fuse box issues, and a Pre-Safe system warning accompanied by spontaneous deceleration. None of these auxiliary electrical problems have been addressed through recalls or service bulletins.
Same Mercedes-Benz E-Class electrical reports on nearby years: 2010 · 2013 · 2014
Failure modes owners describe
Oil leakage into electrical system from cam solenoids/sensors
Camshaft adjustment solenoids and cam sensors leak oil internally, which migrates through the engine wiring harness via capillary action to O2 sensors, oxygen probes, connectors, and the DME (Digital Motor Electronics/ECU). Oil contamination causes component failures, rough running, stalling, and potential complete engine shutdown without warning. Owners report this as a widespread defect that Mercedes addressed in recalls for earlier model years but did not extend coverage to 2012 E-Class vehicles despite the identical problem occurring on this generation.
When: Reported from 48,000 miles onward; one owner experienced recurrence at 116,000 miles after initial dealer repair
Symptoms owners cite: Vehicle runs in full rich mode; Rough running and stalling; Engine compartment component damage; Oil visible in wiring harness; Engine noise and multiple warning messages on display; Potential engine shutdown during driving
Codes mentioned: Pre-Safe inoperative warning (narrative #5)
Repairs/costs cited: Owners cite repair costs ranging from $5,000 to $8,000+. One owner paid $800 for initial diagnosis and was advised not to drive the vehicle. Dealer replacement of cam solenoids performed at 48,000 miles in one case; defect recurred at 116,000 miles.
Recalls/TSBs owners mention: Mercedes previously issued recalls for this defect on earlier model years but did not extend coverage to 2012 model year. Mercedes-Benz acknowledged knowing how to repair the problem but declined warranty coverage, citing cost. No active recall or TSB addressing 2012 model year oil contamination.
Electronic ignition switch failure causing unintended transmission shift to Park
The electronic ignition switch fails to recognize the key, causing the transmission to shift into Park suddenly and without warning while the vehicle is in motion at speeds ranging from below 5 mph to up to 6 mph. The failure is intermittent and unpredictable. One owner reported the vehicle entering Park multiple times in succession immediately upon shifting back to Drive. Another owner experienced the failure in the middle of an intersection. The vehicle stops violently, creating a hazard for traffic behind. One service bulletin (LI54.25-P-056472) documents this issue, but Mercedes has refused warranty repair on out-of-warranty vehicles, claiming the bulletin is not a safety recall.
When: Failure mileage reported at 66,400 miles; another at 72,000 miles; failures occur during warmer weather according to one narrative
Symptoms owners cite: Transmission shifts to Park while driving at low speeds without driver input; Abrupt vehicle stop without warning; Intermittent and unpredictable recurrence; Key not recognized by ignition system; Vehicle can be shifted back to Drive but immediately reverts to Park
Codes mentioned: Service Bulletin LI54.25-P-056472
Repairs/costs cited: One dealer replaced the ignition switch and resolved the failure. Owners report no specific repair cost details in narratives.
Recalls/TSBs owners mention: Service Bulletin LI54.25-P-056472 exists for this issue. Mercedes-Benz has declined out-of-warranty coverage, stating that service bulletins are not safety recalls. Owners indicate Mercedes is aware of the problem but treats it as a non-safety issue.
Backup camera intermittent failure/black screen
The backup camera display shows a blank or black screen approximately 50% of the time when the vehicle is placed in Reverse. The system requires shutdown and restart to restore camera functionality. The malfunction tends to occur on rainy days when the camera is most needed. One owner reports the problem began approximately 2 years prior and has been ongoing. Mercedes dealers have run diagnostics without identifying a fault. A recall exists for earlier model years but does not include 2012 E350.
When: Problem onset approximately 2 years before complaint; failure mileage not specified
Symptoms owners cite: Black screen or no picture on backup camera display; Intermittent failure, approximately 50% of the time in reverse; More frequent in wet/rainy conditions; System requires restart to restore function
Repairs/costs cited: No repair completed. Dealer diagnostics found no fault.
Recalls/TSBs owners mention: Recall exists for earlier model years; 2012 E350 excluded from coverage. No TSB or warranty solution offered for affected 2012 vehicles.
Distronic Plus (Adaptive Cruise Control) unexpected disengagement
The Distronic Plus adaptive cruise control system disengages unexpectedly when the vehicle is coming to a stop in traffic or during stop-and-go driving. The system emits a single beep and flashes a red light, but these alerts are easily missed if the radio is playing or the driver is distracted. This has nearly caused multiple rear-end collisions, prevented only by quick driver intervention.
When: Not specified
Symptoms owners cite: System disengages unexpectedly in low-speed or stop-and-go traffic; Single beep and red light alert easily missed; Nearly caused rear-end collision hazard; Required driver intervention to prevent accident
Repairs/costs cited: No repair completed; vehicle out of warranty.
Recalls/TSBs owners mention: No dealer action taken or TSB provided; vehicle out of warranty.
Wiring harness defect affecting trunk latch
A defective wiring harness in the trunk prevents the trunk lid from opening. The vehicle was diagnosed at a dealership as requiring wiring harness replacement.
When: Failure mileage approximately 70,000
Symptoms owners cite: Trunk lid will not open
Repairs/costs cited: Wiring harness replacement required; repair not completed.
Recalls/TSBs owners mention: No manufacturer notification provided.
Fuse box failure with secondary airbag warning
The vehicle failed to start and illuminated an airbag warning indicator. Diagnosis revealed a faulty fuse box that required replacement. An independent mechanic initially diagnosed a dead battery, but the Mercedes dealership identified the fuse box as the root cause.
When: Failure mileage 81,000
Symptoms owners cite: Vehicle fails to start; Airbag warning indicator illuminated
Repairs/costs cited: Fuse box replacement required; repair not completed.
Recalls/TSBs owners mention: No manufacturer notification.
Seat belt fracture with electrical failures
The driver's side seat belt fractured when the driver attempted to fasten it. Concurrent electrical failures occurred in the vehicle. The dealership determined the seat belt required reprogramming rather than replacement.
When: Failure mileage 25,500
Symptoms owners cite: Seat belt fracture when fastening; Electrical failures in vehicle
Repairs/costs cited: Seat belt reprogrammed at dealer; repair completed.
Recalls/TSBs owners mention: No manufacturer notification.
Pre-Safe system inoperative warning with spontaneous deceleration
A Pre-Safe inoperative warning message appeared on the display while the vehicle was traveling at 45 mph, accompanied by spontaneous vehicle deceleration. The owner coasted to a stop and restarted the vehicle, after which it returned to normal operation. However, the failure recurred once the owner arrived home.
When: Failure mileage approximately 72,000
Symptoms owners cite: Pre-Safe inoperative warning message displayed; Spontaneous deceleration while driving at 45 mph; Failure recurs intermittently
Codes mentioned: Pre-Safe inoperative
Repairs/costs cited: Vehicle not diagnosed or repaired.
Recalls/TSBs owners mention: Manufacturer not notified; no TSB or recall identified.
Synthesized from 14 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 1 most recent
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Common questions
How serious is the electrical problem on the 2012 Mercedes-Benz E-Class?
It's a documented issue but not catastrophic. 14 complaints have been filed. Repairs average $850 and most owners catch it before it causes a breakdown.
At what mileage does the electrical typically fail?
Across the 8 complaints that reported odometer mileage, most electrical failures cluster between 66,400 and 101,000 miles, with the median around 72,000. A quarter of owners report trouble before 66,400; a quarter make it past 101,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
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/2012/Mercedes-Benz/E-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.