Engine

P0227 — Throttle/Pedal Position Sensor "C" Circuit Low Input

Severity: medium Drive with care, to a shop

What P0227 means

The engine control unit monitors the voltage signal from the throttle or accelerator pedal position sensor, channel "C". Normally the signal changes smoothly as you press the pedal, and the sensor channels are compared against each other. P0227 sets when channel "C" voltage falls below the expected range, due to an open circuit, a short to ground, lost sensor supply or a failed sensor.

Symptoms

  • Check Engine light on
  • Reduced power or limp mode
  • Unresponsive or erratic throttle response
  • Rough idle or stalling
  • Higher fuel consumption
  • Poor acceleration

Possible causes

  1. Failed accelerator pedal or throttle position sensor
  2. Damaged wiring, with the signal wire open or shorted to ground
  3. Corroded or loose connector at the sensor
  4. Missing 5 V reference or poor sensor ground
  5. ECM input circuit fault (uncommon)

How to diagnose

  1. Read all codes and freeze-frame data, clear the code and see if it returns
  2. Inspect the pedal and throttle wiring and connectors for chafing, moisture, corrosion or bent pins
  3. Watch the channel "C" reading on a scan tool while pressing the pedal slowly; it should be smooth with no jumps or dropouts
  4. Use a multimeter to check the 5 V reference and ground at the sensor connector
  5. Test the signal wire for opens and shorts to ground using the wiring diagram
  6. Wiggle the harness while monitoring the scan tool to find an intermittent connection
  7. If wiring is good, test the sensor by substitution with a known good part or with a scope
  8. Suspect the ECM only after ruling out wiring and the sensor

Common fixes

  • Replace the accelerator pedal assembly (the sensor is usually part of it) or the throttle body
  • Repair or replace damaged wiring and connectors
  • Restore sensor power and ground, and clean the terminals
  • Reflash or replace the ECM if confirmed faulty

Questions and answers

What does P0227 mean?

The ECM detected low voltage in the throttle or pedal position sensor "C" circuit. The usual culprits are wiring, a connector or the sensor itself.

Can I drive with P0227?

Only carefully and to a shop soon. The car may enter limp mode with reduced power, and throttle response can be unpredictable.

How do I clear P0227?

You can erase it with a scan tool, but it will return unless the cause is fixed. Find the sensor or wiring fault first.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.