OBD codes / P0221
P0221
ModerateThrottle/Pedal Position Sensor B Range/Performance
If the car has dropped into reduced-power mode, it's usually drivable to a shop, but acceleration is limited and throttle response can be unpredictable — risky when merging or crossing traffic. Drive gently, avoid highways if you can, and get it diagnosed promptly rather than living with it.
What this code means
Modern electronic throttle systems use two position sensors ('A' and 'B') on the throttle body or pedal so the computer can cross-check them. P0221 sets when sensor B's signal is out of its expected range or doesn't track plausibly against sensor A and actual engine load. Unlike a hard circuit code, this is a 'the signal exists but doesn't make sense' fault — a worn sensor track, a connector with corroded pins, or wiring with intermittent resistance are typical causes. On most electronic throttle bodies the sensors are built in, so a bad sensor B often means replacing the throttle body (or the pedal assembly, if B lives on the pedal in your vehicle). Because the computer can no longer fully trust the throttle reading, many cars respond by limiting power (limp mode) until the fault is fixed.
Symptoms you might notice
- Reduced-power or 'limp' mode with limited acceleration
- Hesitation, surging, or erratic throttle response
- Rough or unstable idle
- Intermittent symptoms that come and go with bumps or temperature
- Check-engine light
What it costs to fix
Typical range: $50–$600 · about ~0.3–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Connector / wiring repair | $10–$120 | ~0.5–1.5 hrs |
| Throttle position sensor (where separately replaceable) | $40–$200 | ~0.3–1 hrs |
| Electronic throttle body (sensors integrated) | $150–$500 | ~0.5–1.5 hrs |
On older cable-throttle engines the TPS is a cheap bolt-on sensor; on most modern electronic throttles the sensors are sealed inside the throttle body, pushing the cost up. Always rule out the connector and wiring first — they're the cheap fix.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0221 for my exact vehicle →
Frequently asked
Why did my car go into reduced-power mode with P0221?
The computer cross-checks two throttle sensors, and when sensor B stops tracking sensibly it can no longer trust the throttle reading. Limiting power is a deliberate safety response — it prevents an untrusted throttle from accelerating the car unexpectedly.
Is P0221 the sensor or the wiring?
Either. A worn sensor track inside the throttle body is common, but a corroded connector or intermittent wiring produces the same 'implausible signal' fault for far less money. Watching sensor A and B on a scan tool while wiggling the harness is a quick way to tell.
What's the difference between P0221 and P0121?
Same type of fault, different sensor: P0121 is a range/performance problem on sensor A, P0221 is the same problem on sensor B. Both sensors usually live in the same throttle body or pedal assembly, so the diagnosis is similar.
Can I just clean the throttle body for P0221?
Cleaning helps codes caused by carbon binding the throttle plate, but P0221 is a sensor-signal fault — cleaning rarely fixes a worn sensor track. It's still worth cleaning the connector contacts and checking the wiring before buying a throttle body.
Seeing P0221 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0221 for my vehicleRelated trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0221 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.