Parts for your 2012 Subaru Forester-Crank angle sensor

2012 Subaru Forester crank angle sensor: what it does and when to replace it

Yes, the 2012 Subaru Forester is fitted with a crank angle sensor (also called a crankshaft position sensor, CKP). This isn’t an optional extra — it’s essential for engine management on both the FB25 non‑turbo and EJ25 turbo variants used in different markets. Subaru’s Factory Service Manual for MY2012 Forester lists CKP-related diagnostics (DTCs P0335–P0339) and test procedures, and the Subaru FAST/OEM parts catalogue shows a dedicated crankshaft position sensor for these engines. Those technical sources confirm the part is present and critical to operation.

On this Forester, the crank angle sensor tells the ECU exactly where the crankshaft is in its rotation and how fast it’s spinning. That timing info lets the ECU fire the injectors and spark at the right moment, keep idle stable, and coordinate with the cam sensors for variable valve timing. If the sensor signal drops out or goes skew‑whiff, the engine won’t start or will run rough as guts.

Common signs it’s on the way out include:

• Hard starting or a no‑start when hot, then fires up again once cooled
• Random stalling at idle or when coming to a stop
• Misfires, hesitation, or a flat spot off the line
• Check Engine Light with codes like P0335/P0336

There’s no scheduled replacement interval — it’s a “inspect and replace if faulty” item. During servicing, it’s smart to check the wiring loom and connector near the front of the engine for oil intrusion, corrosion, or chafing, especially around the timing cover. Keep the connector clean and seated properly, poor contact can mimic a failed sensor.

Replacement is straightforward for a competent DIYer: disconnect the battery, remove any intake ducting in the way, unplug the sensor, undo the retaining bolt, and pull it straight out. Lightly oil the O‑ring on the new unit, install squarely, and torque the bolt snug (about 8–9 N·m). Don’t shim or adjust it — it’s a fixed‑gap Hall‑effect sensor. After refit, clear codes and crank, no coding is typically required, and the ECU will relearn trims as you drive.

If the Forester intermittently dies when hot or logs CKP codes, don’t muck about — fit a quality OEM‑spec sensor. It’s a small part that prevents big headaches.

FAQs

Where is the crank angle sensor on a 2012 Forester?
It’s mounted at the front of the engine block near the crank pulley/timing cover area. Access is usually from the top with the intake snorkel out of the way. On both FB25 and EJ25 layouts, look low and forward on the block for a small two‑wire sensor held in with a single bolt.

What happens if the crank angle sensor fails on this model?
You’ll often get a no‑start, hot‑soak starting issues, stalling, or harsh misfires. The Check Engine Light may log P0335/P0336. Because the ECU loses precise crank timing, it can’t manage spark and fuel correctly, so the engine either runs poorly or not at all.

Do I need to program a new sensor?
No special programming is usually needed. Fit the new sensor, reconnect the battery, clear any codes, and take it for a gentle drive. The ECU will adapt fuel and idle trims on its own. If codes persist, check wiring, grounds, and the reluctor ring condition.