P2791
Gate Select Direction Circuit Low
Transmission / shift actuator
Generic OBD-II
Medium
What it means
P2791 means the transmission controller sees low voltage on the gate-select direction circuit — part of the actuator system that moves the shift mechanism between gear gates on automated-manual and dual-clutch transmissions. Because it controls gear selection, a fault here can cause hard or failed engagement and limp mode, so it shouldn't be ignored.
Medium
Can I keep driving? Sometimes — the transmission may fail to select gears or drop into limp mode; drive gently and get it checked before it strands you.
Common symptoms
What you'll notice
- Check-engine light on, often with a transmission warning
- Hard, delayed, or failed gear engagement
- Transmission stuck in one gear or in limp/failsafe mode
- Grinding or no drive when selecting a gear (automated-manual/DCT)
Common causes
Most likely first
- Faulty gate-select actuator or its position sensorLikely
- Open or short-to-ground in the gate-select signal circuitCommon
- Corroded or loose connector at the shift-actuator assemblyCommon
- Low or contaminated transmission fluid affecting actuator hydraulicsLess often
- Transmission control module fault (least likely)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and scan for other shift-actuator or fork codes.
- Check transmission fluid level and condition first.
- Inspect the gate-select actuator connector and wiring for a short to ground or open circuit.
- Measure the actuator/sensor signal voltage against spec through its travel.
- If the circuit is good, test the gate-select actuator; replace if faulty. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2791?+
Only cautiously. The transmission may not select gears reliably and can enter limp mode, so have it diagnosed before it leaves you unable to move.
Can I just clear P2791?+
It usually returns quickly. This is an internal shift-mechanism fault that needs the actuator or wiring repaired.
Related codes
Often seen with P2791
Read & clear P2791 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX