A short to voltage on the sensor 'C' signal wire, often from chafed insulation against a metal bracket or another harness.; A failed throttle or pedal position sensor 'C' internally shorted, sending a high voltage signal.; Corroded or pushed-back pins at the sensor connector or the engine computer connector.; A faulty engine computer driver circuit for the sensor reference or signal return, though this is less common.; Water intrusion into the sensor connector or throttle body housing causing a conductive path.; Aftermarket wiring repairs or accessories tapped into the sensor circuit creating an unintended voltage feed.

DTC codes / P02xx · Fuel and air metering (injector circuits) / P0228

P0228Throttle/Pedal Position Sensor/Switch 'C' Circuit High

Q: What does code P0228 mean?

Throttle/Pedal Position Sensor/Switch 'C' Circuit High. P0228 means the engine computer has detected an abnormally high voltage on the signal circuit for throttle or pedal position sensor 'C', which is typically the second or redundant sensor in a drive-by-wire throttle system. The computer expects this signal to stay within a specific low-voltage range at rest and rise smoothly as the throttle is pressed, so a voltage above the upper limit tells it the circuit is shorted to power or the sensor has failed.

P0228 means the engine computer has detected an abnormally high voltage on the signal circuit for throttle or pedal position sensor 'C', which is typically the second or redundant sensor in a drive-by-wire throttle system. The computer expects this signal to stay within a specific low-voltage range at rest and rise smoothly as the throttle is pressed, so a voltage above the upper limit tells it the circuit is shorted to power or the sensor has failed.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

The check engine light or electronic throttle control warning light illuminates steadily.
The engine may enter limp mode, limiting speed to a fast idle or a low fixed RPM.
The accelerator pedal may feel unresponsive or the engine may hesitate when you press it.
Some vehicles may stall or refuse to idle normally after the fault is stored.
Often no symptoms besides the warning light, especially if the redundant sensor still provides a plausible signal.
Cruise control may be disabled or the throttle may feel jerky during light acceleration.

Common causes, most likely first

A short to voltage on the sensor 'C' signal wire, often from chafed insulation against a metal bracket or another harness.
A failed throttle or pedal position sensor 'C' internally shorted, sending a high voltage signal.
Corroded or pushed-back pins at the sensor connector or the engine computer connector.
A faulty engine computer driver circuit for the sensor reference or signal return, though this is less common.
Water intrusion into the sensor connector or throttle body housing causing a conductive path.
Aftermarket wiring repairs or accessories tapped into the sensor circuit creating an unintended voltage feed.

How to diagnose and fix it

Scan all modules and record freeze-frame data for P0228, then clear the code and test-drive to see if it returns immediately.
Inspect the sensor 'C' connector and harness for corrosion, pushed pins, chafing, or signs of water intrusion.
With the key on and sensor connected, back-probe the signal wire and compare its voltage to the manufacturer's specification at rest and through the full pedal travel.
Disconnect the sensor and check for a short to voltage on the signal wire by measuring from the signal pin to battery positive with the key off.
If the wiring passes, substitute a known-good sensor of the same part number and recheck live data to confirm the signal now stays within range.
Check the engine computer connector for corrosion or loose terminals on the sensor 'C' circuit before condemning the computer.
After repair, clear codes, perform any required throttle relearn or idle relearn procedure, and verify the monitor runs to completion.

What a high voltage on sensor C really means

A high voltage code on a position sensor almost always points to a short to power on the signal wire rather than a dead sensor, so inspect the harness before replacing parts.
Many drive-by-wire systems use two or three throttle position sensors whose signals must agree within a small margin, and a single high reading can set P0228 even when the throttle body itself moves freely.
A poor ground or reference voltage shared with other sensors can pull the signal high on one sensor while the others look normal, so check reference and ground circuits at the same connector.
Aftermarket floor mats, pedal covers, or pedal spacers that restrict pedal travel can cause the computer to see an implausible high signal at the top of the pedal range and set this code.
P0228 is often stored alongside P2135 or P0121 when the computer detects that the redundant throttle position signals no longer correlate, so do not chase those codes separately until the high-voltage fault is fixed.

Can I keep driving with P0228?

You can usually drive the vehicle a short distance to a repair shop, but expect reduced power and possible limp mode, so avoid highways and heavy traffic. Do not continue driving if the engine stalls, idles erratically, or the throttle sticks, because that creates an immediate safety risk.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.