Parts for your 2002 Subaru Forester-Throttle position sensors

2002 Subaru Forester throttle-position-sensor: what it does and how to look after it

Yes, the 2002 Subaru Forester is fitted with a throttle position sensor (TPS). Technical sources that confirm this include the 2002 Subaru Forester Factory Service Manual (Engine Diagnostics), which lists TPS-related OBD-II fault codes P0120–P0124 and details TPS signal inspections, and the Subaru parts catalogue for 2002 Forester EJ20/EJ25 engines, which shows a TPS mounted on the throttle body. Common aftermarket service data (e.g., Haynes/Autodata) also specify the TPS output range of roughly 0.5 V at closed throttle to about 4.5 V at wide open, used by the engine control module (ECM) for fuelling and ignition strategies.

On a 2002 Forester’s cable-operated throttle body, the TPS tracks how far the throttle plate is opened by the driver’s right foot. The ECM relies on this to set fuel delivery, ignition timing and deceleration fuel cut, and to help the 4EAT auto manage shift timing and line pressure. When the TPS goes off-song, the Forester can feel flat, surge, hunt at idle or shift a bit harshly, and it’ll often light the check engine lamp with one of those P0120–P0124 codes.

There isn’t a scheduled replacement interval for the throttle-position-sensor, it’s serviced on condition. As part of routine servicing, it’s smart to:

• Scan for fault codes and confirm live data shows a smooth throttle angle sweep from 0% to 100% with no dropouts.
• Inspect the TPS connector and harness for corrosion, hardening or broken wires, especially near the throttle body.
• Clean the throttle body and ensure the throttle cable isn’t binding. Note: cleaning won’t fix a faulty TPS, but it helps keep readings consistent.

If replacement is needed, the job is straightforward: disconnect the battery, unplug the sensor, remove the two retaining screws, fit the new unit and, where applicable, set the base position. Many 2002 Forester sensors sit on slotted holes, they need a quick adjustment so the closed-throttle voltage lands near factory specification (typically around 0.45–0.55 V at closed throttle, or 0% on a scan tool). A short road test to verify smooth throttle response and clean gear changes finishes it off.

Quality matters here. A reputable OEM-equivalent TPS tends to provide stable voltage output and better longevity, which means happier cold starts, crisper tip-in and fewer dramas on long kilometres around Australia and New Zealand.

Popular questions about 2002 Subaru Forester throttle-position-sensors

Does a 2002 Subaru Forester actually have a TPS?
It does. The factory service manual details TPS diagnostics and fault codes (P0120–P0124), and the Subaru parts catalogue lists a throttle position sensor on the throttle body for 2002 Forester EJ-series engines. It’s a key input for fuelling, ignition and auto trans behaviour.

What are the common symptoms or codes of a failing TPS on this model?
Typical signs include hesitation off the line, surging, rough or high idle, poor fuel economy and abrupt shifts on the 4EAT. Common OBD-II codes are P0120 (TPS circuit), P0121 (range/performance), P0122 (low input), P0123 (high input) and P0124 (intermittent). Live-data “dead spots” during a throttle sweep are a giveaway.

Can the TPS be cleaned, or should it be replaced?
The sensor is a sealed electronic unit, so cleaning won’t repair internal wear. Cleaning the throttle body can help drivability, but if the TPS output is erratic or out of spec, replacement is the fix. After installation, set the base position/voltage per service data and verify a smooth 0–100% reading on a scan tool.