What does code P1640 mean?

Q: What does code P1640 mean?

PCM Fault / DTCs Available in Another Module. P1640 on a GM vehicle means the powertrain control module (PCM) has detected an internal fault or has stored diagnostic trouble codes (DTCs) in another module that prevent it from completing its own self-diagnostics. The PCM is essentially reporting that it cannot guarantee its own operation or that another controller on the network is holding codes that affect the PCM's ability to run its tests.

DTC codes / GM codes / P1640

P1640 · GMPCM Fault / DTCs Available in Another Module

P1640 on a GM vehicle means the powertrain control module (PCM) has detected an internal fault or has stored diagnostic trouble codes (DTCs) in another module that prevent it from completing its own self-diagnostics. The PCM is essentially reporting that it cannot guarantee its own operation or that another controller on the network is holding codes that affect the PCM's ability to run its tests.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyProfessional

AreaComputer and output circuits

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