P0221: Throttle/Pedal Position Sensor/Switch "B" Circuit Range/Performance

What does P0221 mean?

The throttle position sensor reports how far the throttle is open, and the pedal position sensor reports how far the accelerator is pressed. Many systems use two signals, "A" and "B". P0221 means the B signal is out of its normal range or does not agree with the other inputs.

On cars with electronic throttle control, the computer compares two or more position signals for safety. When one signal is out of range, many cars limit power (often called limp mode) until the fault is fixed.

Common symptoms

• Check engine light on
• Hesitation or stumble
• Loss of power or poor acceleration
• Hard starting or rough running in some cases

Common causes

The causes below are the ones commonly seen with P0221. The actual cause can vary by vehicle, engine and mileage, so treat this list as a starting point, not a diagnosis.

• A faulty throttle or pedal position sensor
• Damaged, loose or corroded wiring or connectors in the sensor circuit
• A dirty or faulty throttle body

What to check with a scanner

• In Live data, watch throttle and pedal position values while slowly pressing the accelerator with the engine off and key on. They should change smoothly without jumps.
• Read freeze frame data for throttle position and rpm when the code set.
• Check that floor mats cannot press or block the pedal.
• Note related codes such as P0122, P0123 or P2135.

How to read and clear P0221 with OBD Master Pro

1. Plug in your adapter. Connect a generic ELM327 (or ELM329) OBD2 adapter to the diagnostic port, usually under the dashboard on the driver's side. Bluetooth Classic, Bluetooth LE, Wi-Fi and USB OTG adapters are supported.
2. Switch the ignition on. Turn the key to ON or start the engine, depending on your car.
3. Connect in OBD Master Pro. Open the app, go to Connection and pick your adapter. Classic Bluetooth adapters connect from the Bluetooth tab, Bluetooth LE adapters from the BLE tab with no pairing needed. Use the generic OBD2 / EOBD profile or your car's brand profile.
4. Read the codes. Open the fault codes screen to see stored, pending and permanent codes. Confirm P0221 is listed and note any other codes, since they often explain the cause.
5. Check the details. Look at freeze frame data, Live data and, where your car supports it, Mode 06 test results (see the checks above).
6. Fix, then clear. After the repair, clear the codes to turn off the check engine light. Clearing also resets the emissions readiness monitors, so drive normally and check the readiness screen before any inspection. Permanent codes cannot be erased with a scan tool; they clear on their own once the car's self test passes.

Tip: you can also look up P0221 and other codes in the app's DTC search without connecting to a car. If your adapter will not connect, use Connection > Share connection log and email it to support. Many cheap ELM327 clones only handle basic engine OBD2, which is all you need for P0221.

When to see a mechanic

Get professional help if any of these apply:

• The car goes into reduced power mode
• The accelerator does not respond normally
• The throttle body needs cleaning or replacement and relearning

If you are unsure, a qualified technician can confirm the cause with tests such as smoke testing, pressure testing or scope readings. Clearing a code does not repair the fault.

Related trouble codes

See all OBD2 trouble code guides

Related guides

Check engine light on: what to do · How to read an OBD2 code (P, B, C, U) · Stored, pending and permanent codes and freeze frame · OBD2 readiness monitors explained · OBD2 glossary · OBD2 by car brand