801C20

The ZGM (central gateway module) keeps a master list of faults reported by the other control units. A repair-tips page (AutoExplain) prints 801C20 as "central fault memory full - no control unit fault". A reply on an F30-forum thread says a code cannot be cleared while its fault remains, and that because this one means the memory is full, every fault has to be found and cleared before the master memory will clear.

In the one thread read in full, the owner's battery died while driving, a low-voltage warning kept returning after a new battery was registered, and a reply suggested a parasitic drain behind the recurring code. The same owner had checked the wiring and replaced three sensors. That is one owner's account, not a pattern.

Sources disagree on what the code is for. The forum thread and the AutoExplain page read it as "central fault memory full", and AutoExplain lists battery voltage, an unregistered new battery, faults in other modules and wiring as the causes. One code library lists the same number as "recording of the measured data deactivated", and a second repair-tips page (techroute66) says to reprogram the ZGM. No thread read for this page shows a reprogrammed gateway fixing it.