P0228 - Throttle/Pedal Position Sensor/Switch C Circuit High Input
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0228 is set when the Engine Control Module (ECM) detects that the voltage signal from the throttle position sensor (TPS) or pedal position sensor (PPS) circuit 'C' is higher than the calibrated maximum limit, typically exceeding 4.5–4.8 Volts. This usually indicates a short circuit to voltage or a loss of ground in the sensor circuit. Since throttle control is safety-critical, most modern vehicles use multiple sensors (A, B, and sometimes C) for redundancy. A high input fault often triggers a 'limp home' mode to ensure the vehicle remains controllable.
Possible Causes
Signal circuit shorted to voltage (12V or 5V reference)
Open circuit or high resistance in the sensor ground circuit
Faulty throttle body or pedal assembly (internal short)
Corrosion in the ECM connector or internal ECM failure
Symptoms
Recommended Solution
- STEP 1: Inspect connectors at the pedal assembly and throttle body for oxidation or loose pins. Clean with contact cleaner.
- STEP 2: Measure the reference voltage at the connector (should be a stable 5.0V). Test the sensor ground; resistance to chassis ground should be < 0.5 Ohms.
- STEP 3: Use a scan tool to monitor Live Data for Sensor C. If the voltage is stuck at 5V even with the sensor unplugged, there is a short to voltage in the wiring harness.
- STEP 4: If wiring is intact and reference voltage is correct, replace the component (Accelerator Pedal Assembly or Throttle Body). Perform throttle adaptation/relearn procedure if required by the manufacturer.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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