BMW fault code 40A5
Engine electronics
40A5 Monitoring Master/Slave faultpath for coordination drive train (BIT5 is set in status byte)
Module versions: Diesel electronics master (D51MM670), Diesel electronics master (D63MM670)
Which BMWs have these versions 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 40A5 is a BMW code, stored in the car's engine 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 engine electronics is on: 3 Series (E46), Z8 (E52), X5 (E53), 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), Z4 (E85), Z4 (E86), 1 Series (E87), 1 Series (E88), Z4 (E89), 3 Series (E90), 3 Series (E91), 3 Series (E92), 3 Series (E93)
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