Powertrain, generic (extended)

P2791 Gate Select Direction Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2791 is set when the gate select direction signal sits below the lowest value the controller accepts. For a voltage-type sensor this usually points to a short to ground on the signal wire, a missing reference supply or a sensor pulling the line down internally; with switch-type inputs the contact may read as permanently closed to ground. The circuit fault P2790 and the high-side fault P2792 cover the other failure types of the same signal. No manufacturer documents P2791 publicly, so thresholds and debounce times are unknown; the check is one of the out-of-range tests CARB 13 CCR 1968.2 demands for transmission inputs. Measure supply and signal at the sensor connector before replacing the select actuator. The gearbox typically blocks lane changes and may freeze the current gear.

Likely causes

Signal wire chafed and shorted to ground
Sensor reference voltage missing or shorted
Select direction sensor failed with low output

Symptoms

  • No change between shift lanes, limited gear choice
  • Gearbox holds the current gear or selects neutral
  • Transmission warning lamp

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–900
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

gate select sensorwiring harness

Related codes

P2790P2792P0906

References: law.cornell.edu, en.wikipedia.org.