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

What does P0221 mean?

With electronic throttle control the throttle body carries two position sensors, A and B, usually with opposite or offset signals, and the engine module compares them (correlation code P2135). GM and Ford give the pedal sensors their own codes (P2120 ff), so B is in practice the second throttle sensor. P0221 is the plausibility fault: the signal of sensor B is electrically valid but does not match sensor A or the throttle position expected from airflow. Bosch ME9 engines (Saab) set it at a deviation of more than 9 %, older Ford systems at more than 7 degrees between the sensors without the warning light; many newer engines report this only as P2135. The module carries on with sensor A, limits throttle opening and power and switches off cruise control.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Limp mode, reduced power
• Rough idle, jerking
• Cruise control disabled

Common causes

• High Worn track of sensor B (signal jumps)
• Medium Contact resistance at connector or wiring
• Medium Throttle dirty or sticking
• Low Mass airflow sensor fault or false air

Likelihood is a general estimate across vehicles; your make and model may differ.