What it means
The position sensor or switch of transmission range control channel A reports a circuit low condition. The TCM cannot verify the actuator position reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The transmission range control A position sensor or switch reports the A-channel mechanism's position to the transmission control module. This code sets when the A signal voltage is lower than expected, preventing the module from reliably confirming position.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal short in position sensor
- Connector pins corroded - high contact resistance
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Record freeze-frame data and check live data for the selected range and A-channel position to identify when the low reading appears.
- Compare the shifter position with the range reported by the transmission module and note any disagreement.
- Inspect the A sensor connector and signal-wire harness for corrosion, damaged insulation, loose pins, or a wire shorted to ground.
- Check the A sensor signal circuit for a short to ground and inspect terminal contact condition using the wiring diagram.
- Test the A position sensor or switch output against the manufacturer's specification before replacing it.
Common fixes
- Clean and secure corroded A-channel connector terminals.
- Repair the A signal wire where it is shorted to ground.
- Replace the A position sensor if its internal signal remains low.
- Clear the code and confirm that A-channel position readings match selected ranges.
Can I keep driving?
Avoid driving if the transmission misreads the selected range, shifts harshly, or enters limp mode, since gear engagement may be unreliable. If it shifts normally, limit use until the A-channel signal fault is repaired.
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.