Throttle/Pedal Position Sensor/Switch B Circuit High
The Powertrain Control Module (PCM) has detected an abnormally high voltage signal from the Throttle Position Sensor (TPS) or Accelerator Pedal Position (APP) sensor 'B' circuit. This code is set when the sensor's output voltage exceeds the maximum calibrated threshold, indicating a potential short circuit or sensor failure.
This code is highly urgent because a failing throttle position sensor can cause unpredictable acceleration or force the vehicle into a restricted 'limp mode.' It should be diagnosed and repaired immediately to ensure safe vehicle operation.
Common symptoms
- Illuminated Check Engine Light
- Vehicle enters reduced power or 'limp' mode
- Poor or no response when pressing the accelerator pedal
- Erratic or unusually high engine idle
- Engine stalling or hesitation during acceleration
Likely causes
- Faulty Throttle Position Sensor (TPS) or Accelerator Pedal Position (APP) sensor
- Short to voltage in the sensor 'B' signal circuit wiring
- Corroded, damaged, or loose electrical connector at the sensor
- Open ground circuit to the sensor
- Failed Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Inspect the TPS/APP sensor connector and wiring harness
Look for: Look for visible damage, corrosion, pushed-out pins, or loose connections that could cause a poor electrical contact.
Monitor sensor data with an OBD-II scan tool
Look for: Observe the TPS/APP 'B' voltage while slowly pressing the pedal; look for a smooth voltage sweep. A reading stuck at maximum voltage (often near 5V) confirms the circuit high condition.
Test the 5-volt reference circuit
Look for: Use a multimeter to verify the sensor is receiving a steady 5-volt reference signal from the PCM. A reading significantly higher than 5V indicates a short to battery voltage.
Test the sensor ground circuit
Look for: Measure the resistance between the sensor ground pin and the battery negative terminal. High resistance or an open circuit (OL) indicates a bad ground, which can cause the signal voltage to read high.
Check the signal wire for a short to voltage
Look for: Disconnect the sensor and measure the voltage on the signal wire with the key on, engine off. Any voltage present on the disconnected signal wire indicates a short to voltage in the wiring harness.
This page explains the generic P0223 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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