What does code P1623 mean?

Q: What does code P1623 mean?

Transmission Temp Pull-Up Resistor. P1623 on a GM vehicle means the powertrain control module (PCM) has detected an out-of-range voltage on the transmission temperature sensor circuit, specifically the pull-up resistor side that the PCM uses to bias the sensor signal. The PCM expects the sensor to pull the signal voltage down as transmission fluid warms, and when the voltage stays too high or too low for too long, it flags this code.

DTC codes / GM codes / P1623

P1623 · GMTransmission Temp Pull-Up Resistor

P1623 on a GM vehicle means the powertrain control module (PCM) has detected an out-of-range voltage on the transmission temperature sensor circuit, specifically the pull-up resistor side that the PCM uses to bias the sensor signal. The PCM expects the sensor to pull the signal voltage down as transmission fluid warms, and when the voltage stays too high or too low for too long, it flags this code.

SystemPowertrain

Code typeGM specific

SeverityMedium

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.