Parts for your 2004 Subaru Forester-Camshaft sensor

2004 Subaru Forester camshaft sensor — what it does and when to replace it

Yes, the 2004 Subaru Forester uses a camshaft position sensor. This is confirmed by Subaru’s Factory Service Manual for the SG-series Forester (engine diagnostics list DTCs P0340/P0341 for the camshaft position sensor), by OEM parts catalogues that list a camshaft position sensor for the EJ25 engines used in 2004 models (both naturally aspirated and XT), and by mainstream workshop references such as ALLDATA/Mitchell and Haynes manuals that include test and replacement procedures for this sensor.

On a 2004 Forester, the camshaft sensor tells the ECU exactly where the intake cam is in its rotation so the engine can fire injectors and coils at the right time. Paired with the crank sensor, it enables quick starts, smooth idle and proper fuel economy. Most EJ25 variants in this year use a single cam sensor mounted at the rear of the left-hand cylinder head (passenger side on Aus/NZ right-hand-drive vehicles), accessible under the bonnet with basic tools.

It’s not a routine service item, but it’s worth inspecting during major services or timing-belt work (every 100,000 km or as per the service schedule). A failing cam sensor can cause hard starting, a stumble off idle, poor fuel economy, or an engine light with codes like P0340/P0341. Typical checks include confirming a clean, tight connector, looking for oil contamination or cracked wiring conduit, and ensuring the sensor’s O-ring isn’t weeping.

If replacement is needed, it’s a straightforward DIY for a competent home mechanic:

• Disconnect the battery’s negative terminal.
• Unplug the sensor connector and remove the single retaining bolt.
• Gently twist and pull the sensor out, transfer or renew the O-ring.
• Install the new sensor, seat it fully, and tighten the bolt to factory spec (use a small torque wrench).
• Reconnect, clear codes, and confirm a warm idle road test without faults.

Use a quality OEM or reputable aftermarket sensor, cheap copies can cause intermittent faults that look like wiring or ECU issues. If a new sensor doesn’t resolve cam-related codes, inspect the harness near the back of the engine and along the intake manifold, and verify timing-belt condition and alignment, as incorrect cam timing or damaged wiring can mimic a bad sensor.

Popular questions about the 2004 Subaru Forester camshaft sensor

Where is the camshaft sensor on a 2004 Forester?
It’s typically mounted at the back of the left-hand cylinder head (passenger side on Aus/NZ RHD cars). Access is from the top of the engine bay, remove the connector and one small retaining bolt to lift it out. Some turbo and market variants may have minor layout differences, but location remains on the left head.

What symptoms point to a failing camshaft sensor?
Common signs are longer cranking, rough idle, hesitation off the line, a drop in fuel economy, and an engine light with codes like P0340/P0341. Because wiring faults are common, always check the connector and loom before condemning the sensor.

Do I need to program anything after replacing it?
On 2004 Forester EJ engines, no special programming is typically required. Clear the fault codes, start the engine, and let it reach operating temperature. A short drive cycle should restore normal operation if everything is installed correctly.