P2791 indicates the transmission control module (TCM) has detected a low voltage condition in the gate select direction circuit. This circuit monitors the position of the gear selector or transmission range sensor to determine which gear range the driver has selected.
The sensor internal resistance or signal circuit has failed, sending a constant low voltage to the TCM.
Damaged insulation, chafed wires, or a pinched harness pulls the signal voltage below the expected threshold.
Oxidation, bent pins, or a backed-out terminal increases resistance or creates a partial short to ground.
Mechanical misalignment prevents the sensor from reaching the correct position, causing an out-of-range low signal.
The TCM's internal pull-up resistor or input driver for the gate select circuit has failed, but this is uncommon compared to sensor and wiring issues.
Almost never. The code is typically caused by the transmission range sensor, wiring, connectors, or shift linkage. TCM failure is rare and should only be considered after all circuit and sensor tests pass.
The vehicle will likely enter limp mode, limiting speed and gear selection. Continued driving risks further transmission damage or being stranded.
No. P2791 is specific to automatic transmissions with electronic range selection systems.
The underlying fault (sensor, wiring, or mechanical) was not corrected. Clearing codes does not repair the circuit; the TCM will reset the code when the low voltage condition is detected again.