BMW fault code 0400
Engine electronics
In the engine electronics, code 0400 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.
DDE: Exhaust-gas recirculation or exhaust-gas recirculation controller
Module versions: Digital Diesel Electronics (D40M57A1), Digital Diesel Electronics (DDE40KW0)
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.
DDE: Exhaust-gas recirculation (EGR) 2
Module version: Diesel electronics master (DDE41KR0)
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 0400 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: 8 Series (E31), 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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