BMW fault code 4B90
Engine electronics
4B90 Rail Pressure Monitoring at Engine Start
Module version: Diesel engine electronics (D50M47A0)
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 4B90 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), X3 (E83), 1 Series (E87), 3 Series (E90), 3 Series (E91)
Coming soon
Enter your email address to hear when AutoLingo for BMW is ready.