Parts for your 2014 Subaru Forester-Throttle position sensors

2014 Subaru Forester throttle position sensor (TPS) – what it does and servicing tips

Technical references including the Subaru Service Manual for the SJ Forester (2014) and the Subaru parts catalogue specify an electronic throttle body with motor and dual throttle position sensors (TPS), alongside accelerator pedal position sensors. The factory diagnostics list DTCs P0121–P0123 and P2135 for the TPS circuit. That confirms the 2014 Subaru Forester does use a TPS, it’s integrated into the throttle body and isn’t supplied as a separate bolt-on sensor.

On this Forester, the TPS tracks the throttle blade angle and feeds that to the ECU. Paired with the accelerator pedal position (APP) sensors, it lets the ECU command smooth, accurate throttle, manage idle speed, fuel and ignition, cruise control, and stability/traction logic. Subaru uses two TPS tracks inside the throttle body for redundancy, so the ECU can cross-check signals for safety.

Owners generally won’t have a scheduled TPS service item, but keeping the throttle body clean helps. Oil mist and dust can gum up the blade and skew readings. Under the bonnet, a careful throttle-body clean with a sensor-safe cleaner can restore stable idle and response. Don’t force the butterfly by hand on drive-by-wire units. After cleaning or replacement, an idle/throttle relearn via scan tool (or a manufacturer-approved drive cycle) may be needed so the ECU relearns the correct positions.

Common clues a TPS/throttle body is unhappy include:

• Surging, hesitation or rough idle
• Reduced power/limp mode and the check engine light
• Poor fuel economy and throttle lag
• Fault codes like P0121, P0122, P0123 or P2135

A technician can watch live data for TPS% and APP% to confirm a smooth, linear sweep with no dropouts. Intermittent glitches often trace back to connector corrosion or wiring near the throttle body, so checking plugs and grounds is worth it—especially on high-kilometre vehicles.

If the sensor fails, the fix on a 2014 Forester is typically a complete throttle body assembly, as the TPS is built in. Use a new gasket, keep the bore clean, and avoid overtightening. After refit, perform the throttle/idle relearn and clear codes. Choosing a quality (often genuine) throttle body helps avoid calibration mismatches or nuisance faults.

Good preventative habits—fresh air filter, avoiding over-oiled filters, sound battery/charging voltage, and sealing any intake air leaks—go a long way to keeping the TPS readings steady and the Forester driving sweet as.

FAQs

Does the 2014 Subaru Forester have a TPS or just a pedal sensor?
It has both. The throttle position sensor is built into the electronic throttle body, and the accelerator pedal has its own position sensors. The ECU compares them for accuracy and safety.

Can the TPS be replaced on its own?
Not on this model. Subaru supplies the TPS as part of the throttle body assembly. If the sensor is faulty, the usual remedy is replacing the complete throttle body and carrying out an idle/throttle relearn.

Is a relearn needed after cleaning or replacing the throttle body?
Yes, it’s recommended. After cleaning or replacement, a relearn helps the ECU store the correct closed and open positions, improving idle stability and throttle response. Many workshops use a scan tool procedure, some conditions can be learned during a prescribed warm-up and drive cycle.