P0121 means throttle position sensor range/performance. The throttle position sensor's signal doesn't match expected values. You may feel hesitation, surging, or the car going
Drive gently and get it diagnosed within days.
The throttle position sensor's signal doesn't match expected values. You may feel hesitation, surging, or the car going into 'limp mode' with reduced power.
Carbon-track wear — most common.
Carbon buildup restricts movement.
Intermittent signal.
Drive-by-wire units fail as a whole.
Rare.
Typically $50–$600
Throttle body cleaning $50–$150; sensor/body replacement typically $200–$600. Estimates vary by vehicle. Costs are estimates and vary by vehicle, location, and shop.
If the car enters limp mode (reduced power), drive carefully to a shop — don't take the highway. Otherwise schedule soon.
Typically $50–$600. Throttle body cleaning $50–$150; sensor/body replacement typically $200–$600. Estimates vary by vehicle.
Drive gently and get it diagnosed within days.
The most common cause is worn throttle position sensor. Carbon-track wear — most common.