Engine

P0221 — Throttle/Pedal Position Sensor B Circuit Range/Performance

Severity: medium Drive with care, to a shop

What P0221 means

The engine computer compares signals from several throttle or accelerator pedal position sensors against each other and against the commanded throttle angle. P0221 sets when the circuit B signal falls outside the expected range or disagrees with the others. The computer can then no longer control the electronic throttle accurately.

Symptoms

  • Check Engine light on
  • Erratic or unresponsive throttle
  • Reduced power or hesitation when accelerating
  • Rough idle or stalling
  • Limp mode with limited RPM
  • High or unstable idle

Possible causes

  1. Failed throttle position sensor or accelerator pedal sensor
  2. Damaged wiring, open or short in the sensor circuit
  3. Corroded or loose connector
  4. Carbon buildup causing the throttle plate to stick
  5. Electronic throttle body motor failure
  6. Faulty engine computer (rare)

How to diagnose

  1. Read all codes and freeze frame data, then clear the code to see if it returns
  2. Inspect the pedal sensor and throttle body connectors for corrosion, moisture and loose pins
  3. Check the harness for chafing, breaks and shorts to ground or power
  4. With a scan tool, watch pedal and throttle sensor readings as you press the pedal slowly; they should change smoothly and agree
  5. Test the 5 V reference and ground at the sensor with a multimeter
  6. Remove the throttle body and check for carbon buildup and free plate movement
  7. If wiring is good, replace the suspect sensor or throttle body and run a throttle relearn
  8. Suspect the computer only as a last resort

Common fixes

  • Replace the accelerator pedal sensor or throttle body assembly
  • Repair wiring and connectors, clean the terminals
  • Clean the throttle body and perform a throttle relearn
  • Reflash or replace the engine computer (rare)

Questions and answers

Can I drive with a P0221 code?

Only carefully and for a short distance to a shop. Power may be limited and pedal response unpredictable, which is risky in traffic.

Will cleaning the throttle body fix P0221?

Sometimes, if carbon is making the plate stick. If the cause is the sensor, connector or wiring, cleaning won't help, so check the electrical side first.

What does the "B" in P0221 mean?

It identifies the second circuit of the throttle or pedal position sensor. The computer uses multiple circuits to cross-check the signals.

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.