Over 300,000 Mercedes Models Could Roll Away, And It’s All Because Of… Door Locks?

Mercedes-Benz is recalling 310,000 vehicles, including many of its most popular models. In an impressive cascade of failures, a problem with the door locks could lead to the vehicle rolling away. Yes, that seems like a stretch, but it can happen.

A door that can’t tell if it’s open or closed can lead to some other problems, too, that are less about safety and more about convenience.

Corrosion In A Switch Can Lead To Problems

Mercedes-Benz says that in 2021 it started receiving reports of complaints that radios and lights would stay on after drivers got out of the car. At the time, it was treated as a quality failure rather than a safety issue, but the company continued to investigate.

The problem has been narrowed down to corrosion in a microswitch in the doors. In certain conditions, enough moisture can get through the plastic housing of the door lock microswitch. The corrosion won’t stop the doors from locking or unlocking, but it can stop the vehicle from being aware that the door has been opened and that’s causing multiple problems in the vehicle.

Benz said that since 2021 it has received 176 field reports about the main problem the corroded switch causes. That’s a failure to disengage the vehicle’s comfort function – the function that keeps the radio on after you turn off the ignition but is meant to turn it off when you open a door.

How Is This A Safety Concern?

Credit: Mercedes-Benz

The vehicle staying on after you exit can be a problem for owners because it has the potential to drain the battery over time. Though that’s annoying, it’s not likely, and it’s also not really a safety concern. But according to Mercedes-Benz, the safety problem is that if the car doesn’t know the door is open, it might not trigger the function that makes sure the vehicle is in park or engages the electronic parking brake.

Normally, the vehicles would automatically switch the transmission to park, engage the parking brake, or both if they detect the driver failed to do so before getting out. If that safety feature doesn’t work, the vehicle could roll away. Yes, it is a backup for user error, but the backup still needs to work properly.

The list of affected models is long and detailed below. The GLB has the highest number of vehicles included, with more than 70,000 involved.

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This article originally appeared on CarBuzz and is republished here with permission.