Mercedes - fault codes U118A02, B178392, U120B97 - low beam does not switch off
| Data sheet | |
|---|---|
| Manufacturer | Mercedes |
| Vehicle model | 167/177/213/238/257 |
| Year of manufacture | 2017 - 2020 |
| Special features | Models with LED headlights |
| Symptoms | Low beam does not switch off, High Beam Assist not operational; fault codes U118A02, B178392, U120B97 |
Important safety note
In the Mercedes 167/177/213/238/257, a software error in the headlamp control unit may lead to various symptoms
In the above-mentioned vehicles, a software error may cause one headlamp to remain sporadically on after the lights have been switched off.
At the same time, a warning message appears on the multifunction display:
- Low beam faulty
- Adaptive High Beam Assist not operational
In parallel, the following fault codes are often stored in the headlamp control unit:
- U118A02 (headlamp levelling malfunction)
- B178392 (LED drive module fault)
- U120B97 (headlamp malfunction)
In an effort to rule out other causes, check all possible system components and read out/delete the fault memory.
If no errors are identified, update the software (parameter calibration by recoding) of the headlamp control unit. We advise to contact a Mercedes-Benz workshop for this purpose.
This information may also apply to other models and years of manufacture.
Reprinting, distribution, reproduction, exploitation in any form or disclosure of the contents of this document, even in part, is prohibited without our express, written approval; indication of the document source is also required. The schematic illustrations, pictures and descriptions serve only for the purposes of explanation and representation of the instructions and cannot be used as a basis for installation or assembly work. All rights reserved.
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