What does code P1603 mean?

Q: What does code P1603 mean?

Internal Control Module Self Check. P1603 on Volkswagen vehicles means the engine control module (ECM) has run its internal self-check and found a fault within its own processing or memory circuits. The ECM is reporting that its internal diagnostics did not pass, so it cannot guarantee the accuracy of the sensor readings and control outputs it produces.

DTC codes / Volkswagen codes / P1603

P1603 · VolkswagenInternal Control Module Self Check

P1603 on Volkswagen vehicles means the engine control module (ECM) has run its internal self-check and found a fault within its own processing or memory circuits. The ECM is reporting that its internal diagnostics did not pass, so it cannot guarantee the accuracy of the sensor readings and control outputs it produces.

SystemPowertrain

Code typeVolkswagen specific

SeverityHigh

Fix difficultyProfessional

AreaComputer and output circuits

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