What it means
The intermediate shaft speed sensor B (used for closed-loop ratio control on planetary or DCT gearboxes) returns no usable signal. The controller cannot verify ratio change.
At a glance
- Usually lights the check-engine light
How it works
Intermediate shaft speed sensor B measures the speed of the transmission’s intermediate shaft and sends pulses to the transmission control module for ratio control. This code sets when the module receives no usable signal from sensor B, so it cannot reliably verify a gear-ratio change.
Common causes
Most likely first.
- Open sensor element or broken signal wire
- Corroded sensor connector
Symptoms
- Check-engine or transmission warning light on
- Harsh or delayed shifts
- Speedometer or gear indication may behave erratically
- Transmission may enter limp mode
How to diagnose it
- Check freeze-frame data and live transmission speed data to confirm whether intermediate shaft sensor B has no reading while other speed signals are present.
- Inspect sensor B’s connector and harness for disconnection, corrosion, broken wires, or damage near the transmission.
- Check the sensor B circuit for power or reference, ground, and signal continuity as applicable to the vehicle’s design and manufacturer’s wiring diagram.
- If the circuit is intact, test intermediate shaft speed sensor B using the manufacturer’s procedure.
- If sensor B and its wiring pass, inspect the tone wheel or target for damage and confirm the sensor is correctly positioned.
Common fixes
- Reconnect and secure the intermediate shaft speed sensor B connector.
- Repair an open or damaged sensor B circuit wire.
- Clean corroded terminals or replace a damaged connector.
- Replace sensor B if it fails testing with a sound circuit.
- Repair a damaged tone wheel or correct sensor positioning if inspection identifies a target or installation fault.
Can I keep driving?
A missing intermediate shaft speed signal can cause harsh shifts or limp mode, so avoid high speeds, towing, and journeys where losing drive would be hazardous. Stop if the transmission slips, shifts unpredictably, or enters limp mode; continued driving can worsen 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.