BMW fault code 4120
Engine electronics
In the engine electronics, code 4120 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: DDE main relay
Module versions: Digital Diesel Electronics (D50M47A), Digital Diesel Electronics (D50M47B1), Digital Diesel Electronics (D50M57A0), Digital Diesel Electronics (D50M57A1), Digital Diesel Electronics (D50M57B1), Digital Diesel Electronics (D50M57C0), Digital Diesel Electronics (D50M57D0), Digital Diesel Electronics (D50M57E0), Digital Diesel Electronics (D50M57E1), Digital Diesel Electronics (D60M47A0), Digital Diesel Electronics (D60M57A0), Digital Diesel Electronics (D60M57D0), Digital Diesel Electronics (D60PSA0), Diesel fuel electronics (D60TMCA), Digital Diesel Electronics (D62M57A0), Digital Diesel Electronics (D62M57B0), Diesel electronics master (D63MM670), Digital Diesel Electronics (D70N47A0), DDE (d70n47b0) (D70N47B0), Digital Diesel Electronics (D71N47A0), Digital Diesel Electronics (D71N47B0), Digital Diesel Electronics (D71N47C0), DDE (d71n47d0) (D71N47D0), DDE (d73n57b0) (D73N57B0), DDE US-diesel fuel (D73N57C0), Digital Diesel Electronics (DDE50K47)
In: 3 Series (E46) 1998–2006, X3 (E83) 2003–2010, X5 (E53) 1999–2006, Z8 (E52) 2000–2003
4120 Digital Diesel Electronics main relay
Module versions: Digital Diesel Electronics (D72N47B0), Digital Diesel Electronics (D73N47A0), Digital Diesel Electronics (D73N57D0)
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: DDE main relay 1
Module version: Diesel electronics master (D51MM670)
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 4120 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)
Coming soon
Enter your email address to hear when AutoLingo for BMW is ready.