P0123Powertrain
Powertrain · SAE
TPS/Accelerator Pedal Sensor A — High Signal
Meaning
The track A signal voltage of the throttle position or accelerator pedal position sensor exceeds the maximum threshold (typically > 4.8 V). A high signal normally indicates a short to supply voltage or an internally failed sensor.
Common causes
- Short circuit of the signal wire to supply voltage (5 V or 12 V)
- Internally failed TPS/APP sensor (track A shorted to positive)
- Damaged wiring insulation contacting a positive voltage line
- Shorted or deformed connector pins
- ECU fault (rare)
Symptoms
- Check-engine light (MIL) on
- Limp-home mode with power limitation
- Engine does not respond correctly to the accelerator pedal
- Unable to raise engine speed above the limp-home limit
- Possible stall under certain conditions
Severity
High: a continuously high TPS signal simulates wide-open throttle; the engine enters severely restricted limp-home mode.
What to do
- Measure TPS A signal voltage with connector plugged in: must be < 4.8 V
- Disconnect the sensor and measure voltage on the signal wire: if still high, a short to supply exists in the wiring
- Inspect the wiring for contact with positive voltage lines
- Check the connector for pin-to-pin short circuits
- Replace the TPS/APP sensor if the short is internal