Parts for your 2017 Subaru Forester-Camshaft sensor

2017 Subaru Forester camshaft sensor — what it does and how to look after it

Based on Subaru’s own technical literature — the Subaru Technical Information System (2017 Forester Service Manual, Engine/Diagnostics, including DTCs P0340/P0341/P0345/P0346 for Camshaft Position Sensor circuits) and the factory wiring diagrams and parts listings for the FB25 (2.5‑litre) and FA20F (2.0‑litre turbo) engines — the 2017 Subaru Forester is fitted with camshaft position sensors. These engines use Subaru’s AVCS (variable valve timing), which relies on cam sensors to track cam angle in real time, so the part is definitely relevant on this model.

On a 2017 Forester, the camshaft sensor feeds the engine control module with precise cam position data so it can sync fuel injection and ignition and command AVCS adjustments. That means smooth starts, decent fuel economy, lower emissions and strong drivability across the rev range. On FB25 models you’ll typically find sensors on the cylinder heads near the cam ends, turbo FA20F models use multiple sensors to monitor both banks for variable timing control.

This isn’t a routine “replace-by-kilometre” service item, but it benefits from a quick check during scheduled servicing. Keep engine oil changes on time with the correct grade — clean oil helps the AVCS and minimises varnish that can affect the sensor signal. Under the bonnet, look for oil weeping from the sensor O-ring, brittle wiring, or loose connectors. A light film of oil on a magnetic sensor tip can be gently cleaned with electronics-safe cleaner, avoid abrasives.

Common signs a camshaft sensor is on the way out include:

• Hard starting, stalling or rough idle after warm-up
• Flat spots or poor fuel economy
• Check Engine Light with codes like P0340/P0341/P0345/P0346
• Limp-home behaviour and reduced power

Replacement is straightforward for a trained tech and typically a short job: disconnect the battery, unplug the sensor, remove its retaining bolt, swap the O-ring, lightly oil the new seal and refit. Always follow the workshop manual for torque specs and connector routing. After replacement, clear fault codes and perform any required idle or AVCS relearn steps via a scan tool. On twin-bank or turbo variants, diagnose carefully — don’t shotgun both sides unless testing confirms it. Use a quality genuine or reputable aftermarket sensor to avoid nuisance faults.

If the Forester throws a cam sensor code, it’s wise not to keep driving long distances. The car might run, but timing control can be compromised. Get it scanned, confirm power/ground/signal integrity at the plug, and only then replace the sensor to fix the issue properly.

Popular questions about 2017 Subaru Forester camshaft sensors

Where is the camshaft sensor on a 2017 Forester?
The sensors are mounted on the cylinder heads near the camshaft ends, accessible from the top of the engine under the engine cover. FB25 models typically have sensors on each bank, FA20F turbo models use multiple sensors for both intake and exhaust cam monitoring. Exact spots are shown in the Subaru service manual’s engine layout diagrams.

Is it safe to drive with a failing camshaft sensor?
It may start and run, but it can stall, lose power, or default to conservative timing. If the Check Engine Light is on with cam sensor codes, minimise driving and get it checked — extended use could increase fuel consumption and stress other components.

Does a new camshaft sensor need coding?
The sensor itself doesn’t need coding, but it’s good practice to clear codes and, if the scan tool prompts, run an idle/AVCS relearn. That helps the ECM stabilise cam/crank correlation quickly after the repair.