What does code P1664 mean?

Q: What does code P1664 mean?

1-4 Upshift Lamp Control Circuit. P1664 on a GM vehicle indicates that the powertrain control module has detected an abnormal condition in the control circuit for the 1-4 upshift lamp, which is the indicator that prompts the driver to shift from first to fourth gear under light load to save fuel. The computer monitors the circuit for opens, shorts, or unexpected voltage and sets this code when the signal does not match commanded state.

DTC codes / GM codes / P1664

P1664 · GM1-4 Upshift Lamp Control Circuit

P1664 on a GM vehicle indicates that the powertrain control module has detected an abnormal condition in the control circuit for the 1-4 upshift lamp, which is the indicator that prompts the driver to shift from first to fourth gear under light load to save fuel. The computer monitors the circuit for opens, shorts, or unexpected voltage and sets this code when the signal does not match commanded state.

SystemPowertrain

Code typeGM specific

SeverityLow

Fix difficultyIntermediate

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.