What does code P1748 mean?

Q: What does code P1748 mean?

Transmission Control Module Self Test. P1748 on BMW vehicles indicates that the Transmission Control Module (TCM) has detected an internal fault during its power-on self-test, meaning the module's own diagnostic circuitry found a problem within itself or its immediate electrical environment. The TCM runs this self-test to verify that its processor, memory, and output drivers are functioning correctly before allowing normal transmission operation.

DTC codes / BMW codes / P1748

P1748 · BMWTransmission Control Module Self Test

P1748 on BMW vehicles indicates that the Transmission Control Module (TCM) has detected an internal fault during its power-on self-test, meaning the module's own diagnostic circuitry found a problem within itself or its immediate electrical environment. The TCM runs this self-test to verify that its processor, memory, and output drivers are functioning correctly before allowing normal transmission operation.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyProfessional

AreaTransmission

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