Fuel & air metering · Powertrain · generic (SAE-defined)
P0221: Throttle/Pedal Position Sensor/Switch "B" Circuit Range/Performance
P0221 means the "B" throttle or accelerator pedal position signal is electrically present but does not make sense compared with the other position signal or expected engine behavior.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0221 sets
The powertrain control module (PCM) compares the "B" position sensor against the "A" sensor and other inputs such as airflow and rpm. If the "B" signal moves erratically, sticks, or disagrees with the other signal beyond a calibrated tolerance, P0221 sets. The check is a plausibility test rather than an open or short circuit test.
Common causes of P0221
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Worn or dirty track inside the throttle position sensor (TPS)
- Carbon buildup causing the throttle plate to stick
- Failing accelerator pedal position sensor
- Intermittent connector or wiring resistance
- Failed electronic throttle body motor or gears
P0221 symptoms
- Check engine light on
- Reduced power or limp mode
- Surging or uneven idle
- Hesitation when pressing the accelerator
How P0221 is diagnosed
- Check freeze frame data and any companion codes such as P2135 or P0121.
- Inspect the throttle bore for carbon and the plate for sticking with the ignition off.
- Graph both position signals on a scan tool while slowly sweeping the pedal; look for glitches or mismatch.
- Wiggle-test the harness and connector while watching the signal.
- Measure voltage drop on the reference and ground circuits.
Typical fixes for P0221
- Clean the throttle body and perform a throttle relearn
- Replace the electronic throttle body or TPS
- Replace the accelerator pedal assembly
- Repair high-resistance wiring or connections
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0221 FAQ
What does code P0221 mean?
P0221 means the "B" throttle or accelerator pedal position signal is electrically present but does not make sense compared with the other position signal or expected engine behavior. The standard definition is "Throttle/Pedal Position Sensor/Switch "B" Circuit Range/Performance."
Can I drive with a P0221 code?
Possibly, but expect reduced power or limp mode on many vehicles. Keep driving to a minimum and get it diagnosed promptly, since throttle control faults can affect acceleration in traffic.
Can cleaning the throttle body fix P0221?
Sometimes. If carbon is making the throttle plate stick, a careful cleaning followed by a relearn can clear it, but a worn sensor will still need replacement.
How is P0221 different from P0220?
P0220 points to an electrical circuit problem, while P0221 means the signal exists but is implausible or erratic. P0221 more often points to a worn sensor or mechanical throttle issue.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.