What it means
The position sensor or switch of transmission range control channel B reports a circuit/open 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 B position circuit is open, leaving the module unable to verify that channel's position reliably.
Common causes
Most likely first.
- Open in sensor signal wire
- Position switch failed open
- Pin pushed back out of connector body
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 monitor commanded range and B-channel position live data to see when the signal is lost.
- With the vehicle secured, compare the shifter selection with the range shown by the transmission module.
- Inspect the B position sensor or switch connector for a pushed-back pin, corrosion, looseness, or harness damage.
- Check the B sensor signal wire for an open between the sensor and module using the vehicle wiring diagram.
- Test the B position switch or sensor and connector continuity according to the manufacturer's procedure.
Common fixes
- Reseat a pushed-back pin in the B-channel connector and secure the connector.
- Repair an open in the B position sensor signal wire.
- Replace the B position switch if it has failed open.
- Clear the code and verify that B-channel position readings respond consistently to range changes.
Can I keep driving?
Avoid driving if the selected range is not recognized, shifts are missing, or the transmission is in limp mode; the vehicle may not respond predictably. If it still shifts normally, limit driving until the B-channel open 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.