What it means
The ECM detects a circuit low fault on the gear selection actuator position sensor. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
A position sensor reports where the gear selection actuator is, allowing the control module to check whether the requested gear position was reached. This code sets when the sensor signal is lower than the module can use, which can happen if the signal is pulled toward ground or the sensor connection has excessive resistance.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine or transmission warning light
- Delayed or failed gear changes
- Transmission may stay in one gear or enter a limited-operation mode
How to diagnose it
- Record freeze-frame data and check live gear actuator position while selecting gears, noting whether the reading is stuck low or disagrees with the requested position.
- Inspect the gear selection actuator sensor connector and signal wire for corrosion, moisture, damage, or contact with ground.
- Check that the sensor supply and ground are present and sound, following the vehicle wiring diagram and manufacturer's specification.
- With the circuit isolated as specified by the manufacturer, test the signal wire for a short to ground and check connector continuity.
- If the wiring and connections pass, test the position sensor output against the manufacturer's specification and replace the sensor if it remains low.
Common fixes
- Clean and secure corroded or loose sensor connector pins.
- Repair a signal wire shorted to ground.
- Replace a position sensor that tests internally shorted.
- Clear the code and confirm the gear position reading tracks selection during a road test.
Can I keep driving?
Avoid driving if shifts are delayed, fail, or the transmission enters limited operation; the vehicle may not respond predictably in traffic. If it shifts normally, limit driving to a short trip for diagnosis, since the fault can progress to a fixed gear or loss of drive.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.