What does code P1781 mean?

Q: What does code P1781 mean?

Engine Torque Reduction Open Short To Ground. P1781 on Volkswagen vehicles indicates that the engine control module (ECM) has detected an open circuit or a short to ground in the wiring for the engine torque reduction signal circuit. This circuit is used by the transmission control module (TCM) to request reduced engine torque during gear shifts, and a fault here can disrupt communication between the two modules.

DTC codes / Volkswagen codes / P1781

P1781 · VolkswagenEngine Torque Reduction Open Short To Ground

P1781 on Volkswagen vehicles indicates that the engine control module (ECM) has detected an open circuit or a short to ground in the wiring for the engine torque reduction signal circuit. This circuit is used by the transmission control module (TCM) to request reduced engine torque during gear shifts, and a fault here can disrupt communication between the two modules.

SystemPowertrain

Code typeVolkswagen specific

SeverityMedium

Fix difficultyProfessional

AreaTransmission

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