801C20

What the Code Means

801C20 records the deactivation of measured data logging in the body domain controller BCP-ZGM (Body Domain Controller). The logging function itself is part of parameter journaling for diagnostics: once the module disables it, it stops storing measured values.

The cause usually lies in the communication or configuration side of the electrical system: a software fault in the module or low battery voltage that makes the controller interrupt normal operation.

Symptoms

• No specific symptoms that affect handling — the code is often found by accident during diagnostics.
• Warning lights on the instrument cluster are possible.
• Measured data logging is disabled: the module keeps no parameter log, which can complicate later diagnostics.

Diagnosis and Repair

1. Check battery voltage. If it's low, charge the battery and recheck for the code.
2. Run diagnostics through ISTA and clear the fault codes.
3. If an update is available, update the BCP-ZGM software.
4. Check the module memory for related communication faults: if 801C20 returns together with other communication codes, look for the cause on the bus, not in the controller itself.

Secondary Issues

• The main consequence is loss of diagnostic data: the module stops storing measured values, which makes fault-finding harder. This usually isn't critical.
• If you ignore the code, it may point to deeper electrical system problems — for example, chronically low vehicle electrical system voltage or communication faults between modules that will eventually show up in other components.