Parts for your 2009 Subaru Forester-Camshaft sensor

2009 Subaru Forester camshaft sensor — what it does and when to service it

Yes, the 2009 Subaru Forester uses camshaft position sensor(s). This applies to both the 2.5-litre naturally aspirated EJ253 (SOHC with i-AVLS) and the 2.5-litre turbo EJ255 (DOHC with AVCS). Technical sources that confirm this include the Subaru Factory Service Manual (2009 Forester SH, Engine Diagnostics), which details DTCs like P0340/P0345 for camshaft position sensor circuits, Subaru wiring diagrams showing CMP signal lines to the ECM, and Subaru genuine parts catalogues listing camshaft position sensors for these engines.

On this Forester, the camshaft sensor keeps the ECU in the loop about cam phasing so it can fire the injectors and coils at the right moment and operate the variable valve systems smoothly. Lose that signal and you’ll likely cop a check engine light, hard starting, rough idle, misfires, flat spots, and poor fuel economy. In some cases it’ll stall or refuse to start.

There’s no scheduled replacement interval for the sensor, but it’s smart to give it and the loom a once-over during major services (for example, around timing belt time on the EJ253). Oil contamination in the connector, brittle conduit, or metal fuzz on the magnetic tip can all upset the signal.

• Location: EJ253 typically uses one sensor on a cylinder head, EJ255 uses two (one per bank). Access is from the front/top of the engine bay.
• Replacement tips: Disconnect the battery, unplug the connector, remove the retaining bolt, and withdraw the sensor straight out. Lightly oil the O-ring on the new unit, install, and tighten the bolt to factory spec (small M6 fastener torque — check the FSM for the exact value). Clear DTCs and perform an idle relearn if required.
• Quality: Stick with OEM or high-quality aftermarket sensors, cheapies can cause intermittent faults that are a pain to chase.
• Diagnostics: If a code specifies a particular bank/sensor, don’t shotgun parts. Inspect wiring, terminals, and engine grounds first.

Technical sources referenced: Subaru Factory Service Manual (2009 Forester SH, Engine/Diagnostics), Subaru OBD-II DTC listings for P0340/P0345 series, Subaru engine wiring diagrams for EJ25, and Subaru genuine parts catalogues for 2009 Forester camshaft position sensors.

Popular questions

Where is the camshaft sensor on a 2009 Forester?
It’s mounted on the cylinder head and reads a trigger on the camshaft. The EJ253 generally has one sensor, the EJ255 turbo has one on each bank. Access is usually straightforward from the top/front of the engine — look for a small, single-bolt sensor with a two- or three-pin connector.

What are the symptoms of a failing camshaft sensor on this model?
Common signs include a check engine light (often P0340/P0345 family), long crank or no start when hot, rough idle, hesitation, misfires, and higher fuel use. Intermittent faults can feel like random cut-outs or flat spots as the ECU loses sync.

Can it be driven with a bad camshaft sensor?
It might start and run poorly, or not at all. Driving with a flaky sensor can leave the car stranded and risks unburnt fuel in the exhaust. Best bet: diagnose, tidy up wiring/connectors, and replace the sensor promptly.