Parts for your 2015 Subaru Impreza-Throttle position sensors

2015 Subaru Impreza throttle position sensor (TPS)

Yes, the 2015 Subaru Impreza uses throttle position sensors. Subaru’s 2015MY Impreza Factory Service Manual details an electronic throttle control (ETC) system with dual throttle position sensing built into the throttle body and accelerator pedal position sensors on the pedal. The FSM’s Engine/Diagnostics coverage for DTCs P0121, P0122, P0123, and P2135 specifically references throttle position sensor circuits and correlation checks. Subaru parts catalogues for this model year also list the throttle body as an assembly containing the motor and TPS, confirming the sensor is integral rather than a separate bolt-on piece.

On this Impreza, the TPS tells the engine control module exactly how far the throttle plate is open, so fueling, ignition timing, and idle control stay smooth and efficient. Because it’s a drive‑by‑wire setup, precise TPS feedback is critical for throttle response and cruise control behaviour, as well as emissions and economy on long Kiwi and Aussie runs.

As part of regular servicing, the TPS itself isn’t a routine replacement item. What does help is keeping the electronic throttle body clean and the wiring healthy. Every 40,000–60,000 kilometres, a careful clean of the throttle plate and bore with a sensor‑safe throttle body cleaner can prevent sticky operation that feels like laggy response off the lights. Don’t force the throttle plate by hand and avoid soaking the electronics—light, targeted cleaning with the battery disconnected is the go.

If there are drivability issues or the check engine light with codes like P0121–P0123 or P2135, start with inspections under the bonnet: look for loose connectors, rubbed wiring near the throttle body, or moisture in plugs. Because the TPS is integral to the throttle body on the 2015 Impreza’s FB-series engine, replacement typically means fitting a complete throttle body assembly and installing a new gasket. After any replacement or a flat battery, a throttle/idle relearn may be required, follow the Subaru service procedure or use a scan tool capable of ETC resets.

• Common symptoms of TPS/throttle body issues: erratic idle, flat spots on take-off, cruise control dropping out, poor fuel economy, or “limp” mode.
• Best practice: use OEM-quality parts, follow factory torque specs for the throttle body, and perform a relearn so the ECM knows the new throttle plate positions.

Popular questions about 2015 Subaru Impreza throttle position sensors

Does the 2015 Impreza have a separate TPS, or is it built into the throttle body?

It’s built into the electronic throttle body as part of the drive‑by‑wire system. The accelerator pedal also has its own position sensors. If the sensor fails on the throttle body, the usual fix is to replace the complete throttle body assembly rather than a standalone TPS.

What are the signs the TPS is playing up on a 2015 Impreza?

Look for hesitation on light throttle, erratic idle, cruise control cutting out, or the check engine light. Scan tool codes like P0121–P0123 or P2135 are common clues. Before replacing parts, check for dirty throttle deposits, dodgy connectors, or damaged wiring.

Is a relearn needed after cleaning or replacing the throttle body?

Often, yes. After cleaning, throttle body replacement, or a battery disconnect, the ECM may need to relearn throttle plate and idle positions. Some relearns happen automatically after a warm-up and idle period, others are best done with a capable scan tool following the Subaru procedure.