What it means
The position sensor or switch of transmission range control channel B reports a circuit high 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 voltage is higher than expected, so the module cannot reliably verify that position.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open 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
- Save freeze-frame data and review live data for commanded range and B-channel position to identify when the high reading occurs.
- Compare the selected shifter range with the range shown by the transmission module.
- Inspect the B sensor connector and harness for corrosion, loose pins, an open sensor connection, or a signal wire touching battery voltage.
- Test the B signal wire for a short to battery voltage and check connector continuity using the vehicle wiring diagram.
- Check the B position sensor or switch output against the manufacturer's specification to determine whether the sensor is open.
Common fixes
- Clean and secure corroded or loose B-channel connector terminals.
- Repair the B signal wire if it is shorted to battery voltage.
- Replace the B position sensor if it is internally open.
- Clear the code and verify that B-channel position data tracks the selected range.
Can I keep driving?
Do not continue driving if the transmission fails to recognize the selected range, slips, or enters limp mode; unreliable gear engagement can be hazardous and worsen damage. If shifts remain normal, keep driving to a minimum until the B-channel signal 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.