P0222Powertrain
Powertrain · SAE
TPS/Accelerator Pedal Sensor B — Low Signal
Meaning
The track B signal voltage of the TPS or accelerator pedal position sensor is below the minimum acceptable threshold (typically < 0.2 V). A low signal indicates a short to ground, an open circuit, or an internally failed sensor on track B.
Common causes
- Short to ground on the track B signal wire
- Open circuit in the track B wiring
- Internal short to ground in the TPS/APP sensor on track B
- Corroded or loose connector contacts causing excessive voltage drop
- Failed 5 V reference supply for the B circuit
Symptoms
- Check-engine light (MIL) on
- Limp-home mode with throttle limitation
- Engine does not respond to the accelerator pedal
- Possible associated code P2138
- Engine speed locked at idle in some cases
Severity
High: low TPS B signal activates limp-home mode; drivability is seriously compromised.
What to do
- Measure TPS B signal voltage at the connector (must be > 0.2 V with pedal released)
- Disconnect the sensor and measure voltage on the signal B wire: if still low, short to ground in the wiring
- Check wiring for open circuits and short circuits
- Verify the 5 V reference supply
- Replace the TPS/APP sensor if the short is internal