What it means
The position sensor or switch of transmission range control channel B reports a circuit range/performance 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 B position sensor or switch reports the B-channel mechanism's position to the transmission control module. This code sets when the signal is present but outside the expected range or fails to track position changes correctly.
Common causes
Most likely first.
- Dirty or oxidised switch contacts
- Sensor mounting misadjusted
- Sensor element aged beyond calibration window
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
- Save freeze-frame data and compare commanded range with B-channel position live data while selecting ranges with the vehicle safely secured.
- Check whether the B position reading changes consistently and agrees with each selected range.
- Inspect the B sensor or switch mounting, contacts, and connector for misalignment, oxidation, contamination, or loose terminals.
- Check the B sensor output for an erratic or out-of-range signal and compare it with the manufacturer's specification.
- Verify B sensor adjustment and wiring integrity using the vehicle wiring diagram and manufacturer's procedure.
Common fixes
- Clean and secure oxidized B-channel switch contacts and connector terminals.
- Adjust the B position sensor mounting according to the manufacturer's procedure.
- Replace the B sensor if its output remains outside the calibration range.
- Clear the code and confirm that B-channel readings follow each selected range.
Can I keep driving?
Avoid driving if B-channel data disagrees with the selected range, shifting is harsh or delayed, or limp mode is active; the transmission may engage unpredictably. If operation remains normal, keep trips short and avoid heavy loads until checked.
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.