P2791 code meaning
Gate Select Direction Circuit Low
Powertrain system Generic code P27xx codes Check engine light
What P2791 means
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.
P2791 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2791
- No change between shift lanes, limited gear choice
- Gearbox holds the current gear or selects neutral
- Transmission warning lamp
Common causes of P2791
- Most likelySignal wire chafed and shorted to ground
- PossibleSensor reference voltage missing or shorted
- PossibleSelect direction sensor failed with low output
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Gate select sensorWiring harness
What each part of P2791 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 7 | Area: transmission. |
| 91 | The exact fault in that area. |
What to do next
- Note P2791 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2791
What does P2791 mean?
P2791 means "Gate Select Direction Circuit Low". P2791 is set when the gate select direction signal sits below the lowest value the controller accepts. It is a generic code, so it means the same on every make.
Is it safe to drive with P2791?
Drive gently and only to a workshop. With P2791 the car can go into limp mode (reduced power) to protect itself.
Will P2791 fail an emissions test?
Yes, it can. P2791 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2791 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P2791 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.