Parts for your 2017 Subaru Impreza-Throttle position sensors

2017 Subaru Impreza throttle position sensors

Based on technical literature for the model, the 2017 Subaru Impreza absolutely uses throttle position sensors. Subaru’s 2017MY Impreza Service Manual (Engine/Diagnostics – Throttle Control System, Subaru TechInfo) and Subaru New Technology training for the FB20 engine describe an electronic throttle body with a built‑in DC motor and dual throttle position sensors (redundant tracks), plus a separate accelerator pedal position sensor. Typical Subaru DTC coverage (e.g., P0121, P0122, P0123, P2135) also confirms the system’s presence and monitoring strategy.

On this Impreza, the throttle position sensors (TPS) are integrated into the throttle body and report the exact angle of the throttle plate to the ECU. That live angle data is crucial for fuelling, ignition timing, idle control, cruise control, emissions, and driveability. The ECU constantly cross‑checks the two TPS tracks against the accelerator pedal sensor, if they don’t agree within a tight tolerance, it can drop into a protection mode to keep things safe.

When a TPS starts to misbehave, the car may show erratic idle, flat spots on take‑off, surging, stalling at lights, higher fuel use, or a “limp” feel with the check engine light on. A scan tool will usually show a mismatch or dead spots in Throttle Opening Angle versus Accelerator Angle, and may log the codes mentioned above.

• There’s no scheduled replacement interval for the TPS, it’s a sealed part of the throttle body. During routine servicing (every 12 months/15,000 km or as per local schedule), it’s smart to inspect the intake tract for dust and oil vapour, and gently clean the throttle bore and plate if deposits are visible. Don’t force the plate open by hand—use the key‑on pedal method or follow workshop procedure.
• If symptoms or codes point to the TPS, check power, ground, and connector condition first. Battery voltage issues can mimic sensor faults.
• When the throttle body is replaced, Subaru specifies an idle/throttle learning procedure using the Subaru Select Monitor (SSM). Some workshops can complete a basic relearn with a controlled idle period and drive cycle, but factory SSM calibration is preferred.
• Use quality throttle body cleaner, replace the gasket if removed, and torque mounting fasteners to the service manual spec.

For Aussie and Kiwi conditions—dust, heat, and plenty of stop‑start—keeping the intake filter fresh and the throttle body clean goes a long way to preserving TPS accuracy and smooth drivability.

Popular questions

Does the 2017 Impreza have a separate TPS or is it part of the throttle body?
It’s part of the throttle body. The assembly contains a motor and two TPS tracks for redundancy. There’s also a separate accelerator pedal position sensor on the pedal, and the ECU compares both sides for safety and precision.

What are the signs of a failing TPS on a 2017 Impreza?
Common clues include rough or high idle, hesitation off the line, surging at cruise, poor fuel economy, or going into limp mode with a check engine light. Scan data may show erratic throttle angle or correlation codes like P0121–P0123 or P2135.

After cleaning or replacing the throttle body, does it need a relearn?
Yes. Subaru recommends a throttle/idle learning procedure via the Subaru Select Monitor. Some workshops can stabilise idle with a key‑on/idle sequence and a brief drive cycle, but the factory SSM process is the reliable way to lock in correct calibration.