Sometimes the part is installed correctly and is still the wrong part. B105E means the sensor fitted at A53/1, the left side airbag and window airbag sensor, is not the type the Mercedes restraint control unit expects.
A53/1 is the sensor that watches for side impact on the left of the vehicle and feeds both the side airbag and the window curtain decision. Mercedes uses several sensor variants across models and equipment levels, and the control unit is coded to expect a specific one. B105E is set when the unit identifies the installed sensor as a different type.
The module is not complaining about wiring here. It is telling you that the sensor answering on that circuit does not match the configuration. That happens when a salvage part came from a different model, when a superseded part number was substituted without checking application, or when the control unit coding describes a vehicle other than the one the sensor is bolted into.
B105E belongs with the hardware codes because it reports what the module found rather than a resistance out of range. The module evaluates sensor identity at every startup, so the code stands as long as the mismatch does. Crash data is unrelated to this check. It is a permanent deployment record that stays in memory until a module reset removes it.
Clearing memory does not make a mismatched sensor into the right one. Fit the correct sensor for the vehicle, or correct the control unit coding if the coding is what is wrong, and the code goes away. Our mail in reset is aimed at modules holding crash data or locked internal faults, which is a different situation than a parts mismatch.
Mercedes-Benz owns this code and the A53/1 component designation. Their documentation ties that designator to the left side airbag and window airbag sensor, and the correct variant is determined by the vehicle data card rather than by physical appearance.
Compare the part number on the installed sensor against the application for this exact vehicle, since that check settles the question faster than anything on a scan tool. Confirm the left and right sensors are on their correct sides. Read the control unit coding next and verify it matches the car equipment list. If the sensor is wrong, we can source the genuine OEM Mercedes side impact sensor for the correct application. Related codes: B1057, B1061, B1615.
Mail us your original module. We restore it to factory-ready condition for a fraction of dealer cost, the same way we have since 1997.
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