Throttle/Pedal Position Sensor/Switch B Circuit
The Powertrain Control Module (PCM) detected a voltage signal from the Throttle/Pedal Position Sensor/Switch 'B' circuit that falls outside the expected normal operating range. This indicates a malfunction in the sensor or its wiring, preventing the PCM from accurately determining the throttle or pedal position.
This code is considered high severity because a faulty throttle position sensor can cause unpredictable acceleration or force the vehicle into a restricted 'limp home' mode. It should be diagnosed and repaired immediately to ensure safe vehicle operation.
Common symptoms
- Illuminated Check Engine Light
- Vehicle enters 'limp mode' with significantly reduced power
- Poor or no response when pressing the accelerator pedal
- Rough or erratic engine idle
- Engine stalling or hesitation during acceleration
Likely causes
- Faulty Throttle Position Sensor (TPS) or Accelerator Pedal Position (APP) sensor
- Damaged, corroded, or loose wiring and connectors in the sensor 'B' circuit
- Dirty or binding electronic throttle body
- Incorrectly adjusted throttle position sensor (on applicable models)
- Faulty Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Visually inspect the wiring and connectors for the TPS/APP sensor.
Look for: Look for frayed wires, corrosion, bent pins, or loose connections that could interrupt the circuit.
Scan for related codes and monitor live data for the TPS/APP 'B' sensor.
Look for: Observe the voltage or percentage reading as you slowly press the pedal; it should increase smoothly without dropping out or spiking.
Test the sensor's 5-volt reference and ground circuits using a multimeter.
Look for: Verify a steady 5 volts on the reference wire and a solid ground; fluctuations indicate a wiring or PCM issue.
Measure the signal wire voltage from the sensor while operating the pedal.
Look for: The voltage should sweep smoothly (typically from around 0.5V to 4.5V, depending on the vehicle) without any dead spots or erratic jumps.
Inspect and clean the electronic throttle body.
Look for: Check for excessive carbon buildup or physical binding that might prevent the throttle plate from moving freely and matching the sensor's expected position.
This page explains the generic P0220 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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