Parts for your 2007 Subaru Legacy-Throttle position sensors

2007 Subaru Legacy throttle position sensors (TPS): what they do and how to look after them

Based on Subaru’s Factory Service Manual for the 2007 Legacy/Outback (BP/BL) and Subaru technical information on the Electronic Throttle Control system, the 2007 Subaru Legacy does use a throttle position sensor. It’s built into the electronic throttle body and feeds the ECU precise throttle plate angle data. Subaru’s parts catalogues for these models list the TPS as part of the throttle body assembly rather than a standalone bolt-on sensor, confirming it’s fitted and relevant to this vehicle.

On the 2007 Legacy, the TPS is a key player in smooth drivability. Working alongside the accelerator pedal position sensor, it tells the ECU exactly where the throttle plate is, so fuel, spark, and idle control stay bang on. That means crisp throttle response, proper kickdown on autos, and stable idle with the air con on. If the TPS signal goes dodgy, the ECU can throw fault codes and may drop into limp mode to protect the engine and transmission.

Servicing-wise, Subaru’s electronic throttle bodies are generally a sealed unit: the TPS isn’t typically replaceable on its own. If the TPS fails or the internal tracks drift out of spec, the fix is usually a complete throttle body replacement. Before going that far, a couple of sensible maintenance steps can save heaps of grief:

• Clean the throttle bore and plate using throttle body-safe cleaner (don’t flood the motor or bearings). Grime build-up can mimic TPS issues by upsetting the plate’s resting position.
• Carry out an idle/throttle relearn after battery disconnection, cleaning, or throttle body replacement. Best done with a proper scan tool, some workshop methods include key-on waits and controlled idling until warm.
• Scan for codes like P0121–P0123, P2135, or related ETC faults, and check live data for smooth, linear throttle angle change with no spikes or dropouts.

Typical warning signs include surging at light throttle, flat spots, random stalling at idle, harsh or delayed shifts (on autos), or cruise control dropping out. If those pop up and cleaning plus a relearn don’t help, testing by a tech with a scan tool is the next step. Where replacement is required, use a quality throttle body assembly, fit a new gasket, torque evenly, and complete the relearn so the ECU knows the new plate limits.

Recommended inspection intervals? Have the throttle body checked and cleaned around every 40,000–60,000 km, especially if most driving is around town.

Popular questions about 2007 Subaru Legacy throttle position sensors

Does the 2007 Legacy have a separate TPS I can replace?
Most 2007 Legacy variants use a drive-by-wire throttle body with the TPS built in. It’s not usually sold separately, so if the TPS fails, the whole throttle body is replaced. Always confirm with the VIN against a parts catalogue, as regional specs can vary slightly.

What faults or codes point to a bad TPS on a 2007 Legacy?
Common codes include P0121–P0123 (TPS circuit range/performance/high/low) and P2135 (throttle/pedal position sensor correlation). You might also see unstable idle, hesitation, or limp mode. Check live data: the throttle angle should rise smoothly with pedal input, without sudden spikes or dead spots.

Do I need to relearn the throttle after cleaning or replacement?
Yes. After cleaning or fitting a new throttle body, the ECU needs to relearn the throttle plate stops and idle control. A scan tool procedure is best practice, without it, the engine may idle high, hunt, or feel laggy until the ECU completes adaptation.