What it means
The second input shaft speed sensor signal jumps or drops out intermittently. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
Input or turbine shaft speed sensor B supplies a speed signal that the module uses with the primary sensor for transmission control. P2768 sets when sensor B’s signal cuts in and out instead of remaining consistent while the shaft turns.
Common causes
Most likely first.
- Sensor connector not fully seated
- Harness chafed against transmission housing
- Connector with intermittent contact under vibration
Symptoms
- Check-engine or transmission warning light on
- Intermittent harsh or delayed shifts
- Speedometer or gear indication may behave erratically
- Transmission may enter limp mode
How to diagnose it
- Review freeze-frame data and monitor live sensor B speed while reproducing the conditions that set the code.
- Inspect the sensor B plug to confirm it is fully seated and check for corrosion or terminals that grip poorly.
- With live data displayed, gently wiggle the sensor B connector and harness to locate any signal dropouts.
- Follow the harness along the transmission housing and look for chafing, pinching, or damage from vibration.
- Check sensor B’s signal and circuit continuity while moving the harness, using the manufacturer's specification.
Common fixes
- Fully seat and secure the sensor B connector.
- Clean corroded connector contacts and restore a sound connection.
- Repair or reroute wiring chafed against the transmission housing.
- Replace a connector with intermittent terminal contact.
- Replace sensor B if its signal still drops out with sound wiring and connections.
Can I keep driving?
Driving may be possible briefly if shifts remain normal, but stop if they become harsh, delayed, or the transmission enters limp mode. Intermittent speed data can cause unpredictable shifting and added transmission wear.
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.