Parts for your 2016 Subaru Impreza-Throttle position sensors

2016 Subaru Impreza throttle position sensor (TPS) — what it does and how to look after it

Technical documentation confirms the 2016 Subaru Impreza uses a throttle position sensor as part of its electronic throttle control. The Subaru Factory Service Manual for the 2012–2016 Impreza (FB-series engine, Throttle Control System) specifies dual throttle position sensor circuits integrated into the throttle body, along with an accelerator pedal position sensor on the pedal assembly. Subaru diagnostic information lists TPS-related DTCs (such as P0121, P0122, P0123 and P2135), and the OEM parts catalogue shows the sensor as part of the throttle body assembly rather than a separate, serviceable item. On that basis, a TPS is absolutely relevant and fitted to the 2016 Impreza.

On this model, the TPS sits within the throttle body and tracks the angle of the throttle plate. The engine control module compares that signal to the accelerator pedal position sensor to decide how much air to let in, then trims fuel, ignition timing and idle accordingly. It also talks to cruise control, traction and stability systems, so smooth throttle behaviour relies on clean, accurate TPS feedback. There’s no mechanical cable and no manual adjustment, it’s a drive‑by‑wire setup engineered for consistency and redundancy.

The TPS isn’t a scheduled replacement item, but it benefits from good housekeeping. A light throttle body clean every 60,000–100,000 kilometres helps prevent sticky plate movement that can be mistaken for a sensor fault. If drivability goes pear‑shaped — think erratic idle, throttle lag, sudden limp mode, or a check engine light with codes like P0121–P0123/P2135 — it’s time for a proper diagnosis. Common culprits include connector corrosion, wiring damage near the throttle body, or contamination around the plate. Because Subaru integrates the sensor into the throttle body, replacement is typically the complete throttle body assembly rather than a separate TPS.

When fitting a new throttle body, use a fresh gasket, avoid harsh solvents on the coated bore, and check the harness routing so it doesn’t chafe. After installation, an ETC/idle relearn is needed — either with a scan tool or by following the Subaru procedure so the ECM can relearn throttle stops and idle airflow. A healthy battery and clean grounds help keep sensor readings stable, and using quality air filtration reduces grime that can upset throttle response. Done right, the TPS and throttle body usually last the life of the vehicle without fuss.

• Typical symptoms of trouble: unstable idle, delayed acceleration, surging, high idle, reduced‑power mode, and TPS‑related fault codes.
• Good practice: periodic throttle body inspection and cleaning, careful handling of connectors, and completing the relearn after any related work.

Popular questions about 2016 Subaru Impreza throttle position sensors

Does the 2016 Impreza use both a TPS and an accelerator pedal sensor?
Yes. It has dual throttle position sensor tracks inside the throttle body and a separate accelerator pedal position sensor on the pedal. The ECM cross‑checks both for accuracy, which is why mismatches can trigger codes and limp mode.

How long should the TPS/throttle body last, and what might it cost to replace?
In normal use it often lasts the life of the car. Replacement tends to happen only when faults arise. Pricing varies, but as a ballpark: Australia typically sees parts and labour in the AU$500–$1,100 range, New Zealand is commonly NZ$600–$1,300, depending on brand, workshop rates and whether a genuine unit is used.

Is a relearn needed after replacing the throttle body or disconnecting the battery?
Yes. The ECM needs to relearn throttle stop and idle airflow. A scan‑tool routine is preferred, though some workshops use a prescribed key‑on/idle sequence and short drive cycle. Skipping this step can leave the idle high, low, or hunting until the module adapts.