A corroded door switch can let a Mercedes roll away after the driver gets out

Mercedes-Benz is recalling more than 310,000 vehicles in the United States after determining that a corroded switch in the driver’s door can quietly disable the feature meant to keep a parked car from rolling. The defect sits in a part most drivers never think about, and it can fail without any warning light or dashboard message.

How the door switch controls the parking brake

The recall, filed with the National Highway Traffic Safety Administration under campaign number 26V481, centers on a micro-switch built into the driver’s door lock. That switch tells the car’s electronic parking brake, marketed by Mercedes as “Auto-Park,” whether the driver’s door has opened. The system uses that signal to automatically apply the parking brake once it detects the driver stepping out. Moisture can work its way into the switch over time and corrode the internal contact surfaces, and once corrosion sets in, the switch can stop registering that the door opened at all. Without that signal, the parking brake may never engage, leaving the vehicle free to roll.

A defect that spans a decade of models

NHTSA’s acknowledgment letter lists 310,667 potentially affected vehicles across an unusually wide range of Mercedes-Benz nameplates: the A-Class and CLA from the early 2020s, several C-Class and CLE variants, and, in the largest numbers, GLA, GLB and GLC crossovers built as recently as the 2026 model year. Model years run as far back as 2019 for the A 220 and as current as 2026 for the GLB 250 4MATIC and AMG GLB35 4MATIC. The spread reflects how widely Mercedes has reused the same door-lock hardware across its compact and crossover lineup over the past several years.

The consequence of a rollaway

NHTSA’s filing is blunt about the stakes: a vehicle rollaway increases the risk of a crash or injury. Unlike a mechanical parking brake that a driver sets by hand, Auto-Park is designed to work invisibly in the background, engaging automatically so the driver never has to think about it. That convenience becomes a liability the moment the underlying sensor fails silently, because a driver who has never manually set a parking brake on this vehicle has no habitual backup step to fall back on. A car parked on even a slight grade, in a driveway or a parking structure, can begin moving before anyone realizes the brake never applied.

What triggered the recall

Mercedes-Benz USA reported the issue to NHTSA on July 24, 2026, five days before the agency’s acknowledgment letter was issued. The filing does not attribute the recall to a single dramatic incident but rather to a pattern identified through the manufacturer’s own field monitoring of the micro-switch’s failure rate over time. The remedy Mercedes has committed to is a full replacement of the driver’s door lock assembly, performed by dealers at no cost to owners.

Rollaway is a documented killer, not a hypothetical risk

NHTSA treats rollaway as its own distinct category of non-traffic crash, separate from collisions that happen while a vehicle is being driven, and the agency’s own statistical research shows why it takes gaps in rollaway prevention seriously. A review of NHTSA’s rollaway data found that from 2012 through 2014, vehicles rolling away on their own killed roughly 360 people who were standing outside the vehicle, close to 120 deaths a year, accounting for nearly a fifth of all non-occupant fatalities recorded in non-traffic crashes during that span; a later five-year review covering 2016 through 2020 found rollaways still made up about 17 percent of those deaths. None of that history is tied specifically to the Mercedes door-switch defect, and as of the recall filing, Mercedes-Benz had not reported any crashes or injuries connected to campaign 26V481 to NHTSA. But it explains why regulators and the manufacturer moved on a defect that has not yet caused a documented incident.

The scale of the campaign is also unusual for Mercedes-Benz this year. It follows three smaller 2026 recalls from the brand, including a battery fire recall covering roughly 11,900 EQB electric SUVs in February, a drive shaft defect recall covering 24,092 vehicles from the 2018 through 2020 model years in April, and an infotainment reset recall covering 144,049 vehicles in May. Combined, those three earlier campaigns cover fewer vehicles than the door-switch recall alone, a reflection of how widely the same door-lock hardware was shared across seven model lines before the corrosion problem was caught.

Timeline for owners to check their vehicles

Owner notification letters are expected to go out starting September 18, 2026, according to the NHTSA filing, though vehicle identification numbers tied to the recall became searchable on NHTSA’s website in late July. Owners who want to check sooner rather than waiting for a letter can search their VIN directly on NHTSA.gov or contact Mercedes-Benz USA customer service at 1-800-367-6372. The agency’s own vehicle safety hotline, 1-888-327-4236, is also available for owners with general questions about the recall process. Given the size of the affected population, dealers are likely to see a steady stream of appointments over the following months rather than an immediate rush, since the door lock swap is a routine service job rather than an emergency stop-driving order.

A hardware fix, not a software patch

Because the failure originates in a physical, moisture-exposed component rather than in vehicle software, there is no over-the-air update that can resolve it. Mercedes owners driving an affected model in the interim are not barred from using their vehicles, but the recall underscores a broader pattern in modern cars: as manufacturers move more safety functions, like setting the parking brake, from manual driver action to automated sensors, a single corroded part can quietly remove a safeguard that used to depend on habit rather than hardware. For the roughly 310,000 households with an affected Mercedes in the driveway, the fix itself is simple and free; the harder part is not noticing anything wrong until the letter, or the VIN lookup, tells them to look.

This article was created with the assistance of AI and reviewed by an editor.

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