Throttle/Pedal Position Sensor/Switch B Circuit Low
The Powertrain Control Module (PCM) has detected that the voltage signal from the Throttle or Pedal Position Sensor 'B' circuit has fallen below the minimum expected threshold. This typically indicates a short to ground or an internal failure within the sensor itself.
This code often forces the vehicle into a fail-safe 'limp mode' with severely restricted acceleration. It should be addressed immediately as it can make the vehicle unsafe to drive in traffic.
Common symptoms
- Illuminated Check Engine Light
- Vehicle enters reduced power or 'limp' mode
- Lack of response when pressing the accelerator pedal
- Rough or erratic engine idling
- Engine stalling or hesitation during acceleration
Likely causes
- Faulty Throttle Position Sensor (TPS) or Accelerator Pedal Position Sensor (APP)
- Wiring short to ground in the sensor 'B' signal circuit
- Corroded, damaged, or loose electrical connector at the sensor
- Open circuit in the sensor 'B' wiring harness
- Failed Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Visually inspect the wiring harness and connectors for the throttle body and accelerator pedal.
Look for: Look for chafed wires, melted insulation, or corroded pins that could cause a short to ground or poor connection.
Monitor live data for TPS/APP Sensor B voltage using an OBD-II scan tool.
Look for: The voltage should typically rest around 0.5V and smoothly increase to about 4.5V as the pedal is pressed; a constant reading near 0V indicates a hard fault.
Verify the 5-volt reference and ground circuits at the sensor connector using a digital multimeter.
Look for: A reading of approximately 5 volts on the reference pin and good continuity to ground on the ground pin confirms the PCM is supplying the necessary power.
Test the signal wire for a short to ground.
Look for: With the sensor and PCM disconnected, check for continuity between the signal wire and chassis ground; any continuity indicates a short in the harness.
Perform a sweep test on the sensor itself using a multimeter or oscilloscope.
Look for: Watch for smooth, linear voltage changes as the throttle/pedal is moved; dropouts or a constant zero reading mean the sensor has failed internally.
This page explains the generic P0222 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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