Faulty throttle position sensor or accelerator pedal position sensor (the 'C' channel) giving a high output; Open circuit in the sensor ground or return wire, causing the signal to read high; Signal wire shorted to the 5 volt reference or battery voltage; Corroded, loose or damaged connector terminals at the sensor or control unit; Faulty throttle body or throttle actuator assembly with integrated sensor; Fault inside the engine control unit.

P0228

Throttle/Pedal Position Sensor/Switch C Circuit High.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
28: FaultThe specific fault in that area

What it means

P0228 means the engine control unit has detected a voltage that is too high from the throttle/pedal position sensor or switch 'C' circuit. The signal has gone above the expected range, which usually points to a short to voltage, an open circuit in the sensor ground or a faulty sensor. Which physical sensor is 'C' depends on the model and engine, so check the manufacturer's data.

Symptoms

Engine warning light on
Car in limp mode with reduced power
Poor or delayed throttle response
Unstable or high idle
Hesitation or surging when accelerating
Engine may stall or be difficult to start

Possible causes

Faulty throttle position sensor or accelerator pedal position sensor (the 'C' channel) giving a high outputlikely
Open circuit in the sensor ground or return wire, causing the signal to read highlikely
Signal wire shorted to the 5 volt reference or battery voltagepossible
Corroded, loose or damaged connector terminals at the sensor or control unitpossible
Faulty throttle body or throttle actuator assembly with integrated sensorpossible
Fault inside the engine control unitrare

How to diagnose

Read all stored and pending codes and note the freeze frame data (engine speed, load, throttle angle) from when the fault set.
Check for related throttle, pedal or reference voltage codes, since they help point to a shared wiring or supply fault.
Inspect the wiring and connectors at the throttle body and accelerator pedal for damage, chafing, water ingress, corrosion or pushed-out pins.
With live data, compare the throttle/pedal sensor channels while slowly pressing the pedal and look for a value stuck high or out of step with the other channels.
Check the 5 volt reference and ground at the sensor connector against the manufacturer's specification.
Test the signal wire for a short to voltage and the ground wire for an open circuit or high resistance, with the connector unplugged and the ignition off where appropriate.
Check the throttle body for sticking or heavy carbon build-up, and look for movement that is not smooth.
Use the manufacturer's procedure to confirm which sensor is 'C' on this model before condemning any part.

How to fix

Repair or replace damaged wiring, including shorts to voltage or open ground wires.
Clean, repair or replace corroded or loose connector terminals.
Replace the faulty accelerator pedal assembly or throttle position sensor if it is serviced separately.
Replace the throttle body assembly if the sensor is integrated and found faulty.
After repair, perform any required throttle or pedal adaptation/relearn, clear the codes and road test to confirm the fault does not return.

Can I keep driving?

Medium severity

The car may go into limp mode with limited power and unpredictable throttle response, so it is best to avoid driving it further than necessary. Get it checked soon, as reduced power can be unsafe in traffic.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.