BMW fault code CF21

Transmission control

CAN message from instrument cluster: outside temperature relative time

Module version: Transmission control (GS30)

In: 3 Series (E36) 1990–2000, 3 Series (E46) 1998–2006, X3 (E83) 2003–2010, X5 (E53) 1999–2006, Z4 (E85) 2002–2008, Z4 (E86) 2006–2008, Z8 (E52) 2000–2003

Reading and clearing it

Fault code CF21 is a BMW code, stored in the car's transmission control, 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 transmission control is on: 8 Series (E31), 7 Series (E32), 5 Series (E34), 3 Series (E36), Z3 (E36/7), 7 Series (E38), 5 Series (E39), 3 Series (E46), Z8 (E52), X5 (E53), X3 (E83), Z4 (E85), Z4 (E86)

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