P0121 Subaru Forester
Throttle/Pedal Position Sensor A Range/Performance · Powertrain Code · High · Repair: Moderate
What is P0121?
The TPS is reading outside expected parameters for the current conditions.
When the Subaru Forester triggers code P0121 (throttle/pedal position sensor a range/performance), it typically points to an issue in the powertrain system. This is a high severity code, so address it promptly to avoid further damage or safety concerns. Below you'll find the most common causes, symptoms, and repair options specific to the Subaru Forester.
This repair is rated moderate, meaning some experience and specialty tools required.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Subaru Forester.
Common Causes on Subaru Forester
- Worn throttle position sensor in the electronic throttle body
- Contaminated throttle body bore
- Throttle body wiring issue
- Failing electronic throttle body motor
Symptoms
- Check Engine Light on
- Erratic idle
- Hesitation on throttle tip-in
- Cruise control may not engage
- Limp mode activation
Notes for Subaru Forester
After cleaning or replacing the throttle body, disconnect the battery for 30 seconds to reset the idle adaptation.