BMW fault code C904
Junction Box electronics
In the junction box electronics, code C904 means different things depending on the version of the module in the car. Find your car below; the app shows the right one for yours.
K_CAN_LOW_LINE
Module version: Junction Box electronics (JBBF87)
In: 1 Series (E87) 2004–2011, 3 Series (E91) 2005–2012, 3 Series (E90) 2005–2012, 3 Series (E92) 2006–2013, 3 Series (E93) 2007–2013
KGM: K-CAN line fault
Module version: Body gateway module (KGM_60)
In: 5 Series (E60) 2003–2010, 5 Series (E61) 2004–2010, 6 Series (E63) 2003–2010, 6 Series (E64) 2004–2010
JBE: K-CAN wire fault
Module version: Junction Box Electronics (SPEG56)
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 C904 is a BMW code, stored in the car's junction box electronics, 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 junction box electronics is on: 5 Series (E60), 5 Series (E61), 6 Series (E63), 6 Series (E64), 7 Series (E65), 7 Series (E66), 7 Series (E67), X5 (E70), X6 (E71), X6 (E72), 1 Series (E81), 1 Series (E82), X1 (E84), 1 Series (E87), 1 Series (E88), Z4 (E89), 3 Series (E90), 3 Series (E91), 3 Series (E92), 3 Series (E93)
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