What it means
The TCM has not learned the end-stop calibration for shift fork B. Engagement positions cannot be commanded with full precision until adaptation completes.
At a glance
- Usually lights the check-engine light
How it works
The transmission control module (TCM) uses learned end-stop positions to command shift fork B accurately. This code sets when the TCM has not learned fork B's travel limits, so it may not position the fork precisely until the adaptation completes.
Common causes
Most likely first.
- Adaptation lost after battery disconnect or TCM reset
- Shift fork replaced without learn procedure
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 all transmission codes and freeze-frame data, then check live data for shift fork B's learned status and commanded position.
- If the fault followed a battery disconnect or TCM reset, check the manufacturer's service information for the correct fork B adaptation conditions and procedure.
- Inspect the transmission connectors and accessible wiring for loose connections, corrosion, damage, or signs of recent work around fork B.
- If fork B was replaced or transmission work was done, confirm the correct parts and installation before attempting the specified learn procedure.
- Run the manufacturer's fork B calibration procedure with a scan tool, then verify that the learned status is complete and the code does not return.
Common fixes
- Complete the manufacturer's shift fork B adaptation procedure.
- Restore a secure, clean connection at any disturbed transmission connector.
- Repair damaged wiring or connector terminals in the shift fork B circuit.
- Correct fork B installation or repair a mechanical fault if calibration will not complete.
Can I keep driving?
Avoid hard acceleration and unnecessary trips until fork B calibration is complete, especially if shifts are harsh or delayed. If the transmission slips, misses shifts, or becomes stuck in one gear, stop driving and arrange recovery to avoid further transmission damage.
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.