What does code P1686 mean?

Q: What does code P1686 mean?

A/T FI Signal B Low Input. P1686 on Nissan vehicles means the Transmission Control Module (TCM) has detected a low input voltage on the Automatic Transmission (A/T) Fuel Injection (FI) signal circuit, which is the communication line carrying fuel injection data from the Engine Control Module (ECM) to the TCM. The TCM expects a specific voltage range on this signal and flags the code when the voltage stays below the acceptable threshold for a set period.

DTC codes / Nissan codes / P1686

P1686 · NissanA/T FI Signal B Low Input

P1686 on Nissan vehicles means the Transmission Control Module (TCM) has detected a low input voltage on the Automatic Transmission (A/T) Fuel Injection (FI) signal circuit, which is the communication line carrying fuel injection data from the Engine Control Module (ECM) to the TCM. The TCM expects a specific voltage range on this signal and flags the code when the voltage stays below the acceptable threshold for a set period.

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.