What does code P1406 mean?

Q: What does code P1406 mean?

Heated Catalyst Internal Control Module Checksum ROM Error. P1406 on BMW vehicles indicates that the heated catalyst control module has detected an internal checksum error in its read-only memory (ROM), meaning the stored program data is corrupted. The module performs a self-check at key-on and flags this code when the calculated checksum does not match the expected value, preventing reliable operation of the heated catalyst system.

DTC codes / BMW codes / P1406

P1406 · BMWHeated Catalyst Internal Control Module Checksum ROM Error

P1406 on BMW vehicles indicates that the heated catalyst control module has detected an internal checksum error in its read-only memory (ROM), meaning the stored program data is corrupted. The module performs a self-check at key-on and flags this code when the calculated checksum does not match the expected value, preventing reliable operation of the heated catalyst system.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaAuxiliary emission controls

Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.