P0228: Throttle/Pedal Position Sensor/Switch "C" Circuit High Input
May trigger limp‑home mode, reduced acceleration, erratic throttle response, and reduced engine performance
Overview
P0228 OBD‑II code indicating a high voltage signal from the throttle/pedal position sensor/switch C circuit above the expected range, often causing reduced performance and potential limp mode
Common Symptoms
- Check engine light illuminated
- Reduced engine power
- Poor acceleration response
- Erratic idle or stalling
- Possible limp mode activation
Most Common Causes
Consistently high voltage readings often originate from sensor internal failure
Damage or corrosion to wiring/connectors between sensor and PCM can produce erroneous high signals
Loose or corroded connections may cause high circuit readings
Rare cases where control module misreads signal or has internal faults
May contribute indirectly by affecting sensor readings
Diagnostic Steps
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Connect a professional OBD‑II scanner and retrieve trouble codes including freeze‑frame dataExpected: Confirmation of P0228 and related codesInterpretation: Verifies presence and context of the high sensor voltage condition
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Visually inspect wiring harness and connectors related to throttle/pedal sensors for damage or corrosionExpected: Identification of damaged, frayed, or corroded wiresInterpretation: Wiring issues are common causes and must be addressed first
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Measure throttle/pedal sensor C circuit voltage with a multimeter during pedal movementExpected: Voltage within expected range (typically ~0.5 to 4.5 V)Interpretation: High observed voltage supports a sensor or circuit fault
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If sensor voltages appear normal, test PCM input for consistency or refer to manufacturer software calibrationExpected: Matching voltage at PCM inputInterpretation: Differing readings between sensor and PCM input could indicate PCM fault
Repair Solutions
Typical when sensor internal circuits fail
Cleaning and securing connections often resolves voltage issues
Useful if carbon buildup affects sensor readings
Consider only after confirmed faults or software calibration issues
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Assuming throttle body mechanical failure without proper sensor/circuit testing
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