What does code P1678 mean?

Q: What does code P1678 mean?

FPTDR Signal Line Failure. P1678 on Nissan vehicles indicates that the Engine Control Module (ECM) has detected a failure on the FPTDR signal line, which is a dedicated communication circuit used for fuel pump control and diagnostics. The ECM monitors voltage and continuity on this line and sets the code when the signal is missing, out of range, or shorted, preventing proper fuel pump command and feedback.

DTC codes / Nissan codes / P1678

P1678 · NissanFPTDR Signal Line Failure

P1678 on Nissan vehicles indicates that the Engine Control Module (ECM) has detected a failure on the FPTDR signal line, which is a dedicated communication circuit used for fuel pump control and diagnostics. The ECM monitors voltage and continuity on this line and sets the code when the signal is missing, out of range, or shorted, preventing proper fuel pump command and feedback.

SystemPowertrain

Code typeNissan specific

SeverityMedium

Fix difficultyProfessional

AreaComputer and output circuits

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