What does code P1378 mean?

Q: What does code P1378 mean?

Cylinder 8 Ignition Circuit Short To Ground. P1378 on a Volkswagen indicates that the engine control module (ECM) has detected a short to ground on the ignition circuit for cylinder 8. The ECM monitors the ignition coil control wire and sees voltage below the expected threshold when the circuit should be inactive, signaling a direct path to ground that prevents proper spark delivery.

DTC codes / Volkswagen codes / P1378

P1378 · VolkswagenCylinder 8 Ignition Circuit Short To Ground

P1378 on a Volkswagen indicates that the engine control module (ECM) has detected a short to ground on the ignition circuit for cylinder 8. The ECM monitors the ignition coil control wire and sees voltage below the expected threshold when the circuit should be inactive, signaling a direct path to ground that prevents proper spark delivery.

SystemPowertrain

Code typeVolkswagen specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

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