What does code P1603 mean?

Q: What does code P1603 mean?

Serial Data Communication Problem. P1603 on a GM vehicle means the powertrain control module (PCM) has detected a fault on the serial data communication bus that links it to other onboard modules. The PCM sets this code when it cannot reliably exchange messages with a module it expects to hear from, such as the body control module (BCM) or anti-lock brake system (ABS) module, and it stores the specific communication failure in its memory.

DTC codes / GM codes / P1603

P1603 · GMSerial Data Communication Problem

P1603 on a GM vehicle means the powertrain control module (PCM) has detected a fault on the serial data communication bus that links it to other onboard modules. The PCM sets this code when it cannot reliably exchange messages with a module it expects to hear from, such as the body control module (BCM) or anti-lock brake system (ABS) module, and it stores the specific communication failure in its memory.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyProfessional

AreaComputer and output circuits

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