What it means
Voltage on the range sensor B signal line is below the expected window. Wire shorted to ground or sensor internal short.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Range sensor B sends a selector-position signal to the transmission control unit. P2802 sets when the B-channel signal voltage is below its expected range, which can happen if the signal is grounded, the sensor is internally shorted, or connector resistance disrupts the reading.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- 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
- Capture freeze-frame data and check the live B-channel voltage or range status to confirm the low reading is present.
- Inspect the range sensor B connector and nearby harness for corrosion, pin damage, or wiring rubbed through to ground.
- With the wiring diagram, check the B-channel signal for a short to ground and inspect its supply and ground connections.
- Disconnect the sensor as directed by the manufacturer’s procedure and determine whether the low signal remains in the harness.
- Test range sensor B output and circuit continuity against the manufacturer’s specification before replacing parts.
Common fixes
- Clean and secure corroded range sensor B connector terminals.
- Repair the B-channel wire where it is shorted to ground.
- Replace range sensor B if its signal remains low with a verified good circuit.
- Repair a poor supply or ground connection identified by testing.
Can I keep driving?
Avoid driving if the transmission cannot identify the selected range, shifts unpredictably, or enters limp mode. Continued operation with unreliable range input can worsen shift problems; stop if the vehicle does not engage the range shown.
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.