Parts for your 2017 Subaru Legacy-Camshaft sensor

2017 Subaru Legacy camshaft sensor — purpose, symptoms, and service tips

Technical sources confirm the 2017 Subaru Legacy does use camshaft position sensor(s). Subaru’s factory service information (STIS) for the 2015–2019 Legacy/Outback details camshaft position sensor diagnostics and replacement in the Engine section, and the Subaru genuine parts catalogue lists “Sensor – Camshaft Position” for 2017 Legacy engines (FB25 2.5L and EZ36 3.6L). The model’s OBD-II diagnostics also include camshaft sensor fault codes (e.g., P0340/P0345), which are documented in Subaru service literature. So yes, a camshaft sensor is fitted and relevant on this vehicle.

On the 2017 Legacy, the camshaft sensor tracks cam angle and speed so the ECU can sync fuel injection, spark timing, and Subaru’s AVCS (variable valve timing). If the sensor signal goes missing or messy, the car may crank longer to start, run rough, lose power with AVCS disabled, or throw the check-engine light with limp-home behaviour. Fuel economy can also take a hit.

This isn’t a routine replacement item, but it deserves attention during scheduled servicing. A sensible approach on a 2017 Legacy includes:

• Visual checks for damaged wiring, loose connectors, oil contamination, or corrosion at the sensor plugs on the cylinder heads.
• Scanning for codes if there’s hard starting, misfires, or odd idle. Codes like P0340/P0345 point straight at the cam sensor circuit.
• Listening and feeling for rough idle or hesitation under load, which may align with timing control being switched off by the ECU.

Replacement is straightforward for a competent DIYer or technician. Always work on a cool engine, disconnect the battery, and clean around the sensor to keep grit out. Unplug the connector, remove the retaining bolt, and gently twist the sensor free. Lightly oil the O-ring on the new sensor, seat it squarely, and tighten the bolt to the factory torque (refer to the Subaru service manual for the correct spec). Clear any fault codes and allow the ECU to relearn at idle. On FB25 models, there are typically two cam sensors (one per bank), so avoid mixing connectors, label them before removal.

Use quality OEM-equivalent parts to maintain reliable AVCS operation. As part of long-term care—especially beyond 100,000 km—keep an eye on harness condition and engine oil quality, because poor oil maintenance can aggravate timing control issues that get mistaken for sensor faults.

Popular questions about 2017 Subaru Legacy camshaft sensors

How many camshaft sensors are on a 2017 Subaru Legacy?
The 2.5L FB25 generally uses two camshaft position sensors, one for each cylinder bank. The 3.6L EZ36 also employs cam sensors per bank. Both setups allow the ECU to monitor cam timing and manage AVCS accurately.

Can the car run with a bad camshaft sensor?
It might start and run, but usually with rough idle, reduced power, and the check-engine light on. The ECU may disable variable valve timing and use a fallback strategy, so it’ll feel a bit gutless and can drink more fuel. Fixing the underlying sensor or wiring issue is the proper cure.

Does a new camshaft sensor need programming?
No special programming is normally needed. Fit the sensor, clear any codes, and let the car idle so the ECU can stabilise trims. If codes return, double-check wiring, connectors, and mechanical timing before assuming the new sensor is faulty.