BMW fault code 0004
Rear-compartment monitor
FMBT: PL lead, open circuit
Module version: Rear-compartment monitor (FOND_BT)
Which BMWs have this version depends on the engine and equipment, so we don't list them here; AutoLingo for BMW reads which version your car has.
Reading and clearing it
Fault code 0004 is a BMW code, stored in the car's rear-compartment monitor, not a generic OBD2 code (P0xxx): a generic OBD2 reader only reaches the engine's emissions faults, so it won't show it. AutoLingo for BMW reads it with BMW's own diagnostic protocols, in plain English, with the details the module stored about it, and clears it after a repair. If a fault comes right back after it's cleared, the problem is still there.
The rear-compartment monitor is on: 7 Series (E38)
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