BMW fault code 940B
Trailer module
AHM: Electric brake, trailer, faulty
Module version: Trailer module (AHM_E65)
In: 1 Series (E87) 2004–2011, 1 Series (E82) 2007–2013, 1 Series (E81) 2007–2011, 1 Series (E88) 2008–2013, 3 Series (E90) 2005–2012, 3 Series (E91) 2005–2012, 3 Series (E92) 2006–2013, 3 Series (E93) 2007–2013, 5 Series (E60) 2003–2010, 5 Series (E61) 2004–2010, 6 Series (E63) 2003–2010, 6 Series (E64) 2004–2010, 7 Series (E65) 2001–2008, 7 Series (E67) 2002–2008, 7 Series (E66) 2002–2008, X1 (E84) 2009–2015, X5 (E70) 2006–2013, X6 (E71) 2008–2014, X6 (E72) 2009–2011
Reading and clearing it
Fault code 940B is a BMW code, stored in the car's trailer module, 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 trailer module 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), X3 (E83), 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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