Parts for your 2021 Subaru Impreza-Crank angle sensor

2021 Subaru Impreza crank-angle-sensor (crankshaft position sensor)

Yes, the 2021 Subaru Impreza is fitted with a crank-angle-sensor, commonly referred to by Subaru as the crankshaft position sensor (CKP). This is confirmed by the 2021MY Impreza Service Manual for the FB20 engine (engine diagnostics and ECM sections), the Subaru Technical Information System (STIS), and Subaru’s genuine parts catalogue, which all list and describe the CKP sensor and related diagnostic codes P0335–P0339.

On the 2021 Impreza, the crank-angle-sensor tracks the exact rotational position and speed of the crankshaft. The engine control module uses this signal to fire the coils at the right moment, inject fuel precisely, coordinate variable valve timing with the cam sensors, and verify combustion for misfire detection. If the sensor drops out, the car may crank for ages, run roughly, stall, or not start at all.

It’s not a regular service item, but it pays to keep an eye on it. During routine services, a technician can scan for CKP-related fault histories, check the wiring and connector for heat or oil contamination, and look for oil leaks at the front timing cover that could seep onto the sensor or reluctor ring. A strong battery and good grounds help keep the signal clean, especially in colder Kiwi and Aussie winters.

• Common symptoms of a dodgy CKP: hard starting or no-start, intermittent stalling, uneven idle, reduced power, and a check engine light with codes like P0335.
• Typical causes: sensor internal failure with age and heat, wiring damage near the front of the engine, or metal debris/contamination affecting the reluctor signal.

Replacement is straightforward but should follow proper diagnosis to rule out wiring or cam sensor issues. Access is at the front of the FB20 engine near the timing chain cover. Disconnect the battery, unplug the sensor, remove the retaining bolt, and twist-pull the sensor free. Inspect and replace the O-ring, lightly oil it, fit the new sensor, torque the bolt to spec, reconnect the harness, clear codes, and confirm stable RPM and sync on a scan tool. Most workshops allow roughly half an hour, though access can vary if intake ducting needs to come off. Genuine or high-quality aftermarket parts are recommended for signal reliability.

Technical sources referenced: Subaru 2021MY Impreza Service Manual (FB20 engine diagnostics, CKP system description and waveform), Subaru Technical Information System (STIS), Subaru OBD-II DTC list (P0335–P0339 for crankshaft position sensor), and Subaru genuine parts catalogue listing for the 2021 Impreza crankshaft position sensor.

FAQs

Where is the crank-angle-sensor on a 2021 Subaru Impreza?
It’s mounted at the front of the engine, adjacent to the timing chain cover on the FB20. Access is typically from the top with the engine cover and intake ducting removed. The wiring harness runs along the front of the block, so technicians also check for rubbing or heat damage there.

Can you keep driving with a failing crank-angle-sensor?
It’s risky. A failing CKP can cause sudden stalling or a complete no-start. Even if it runs, timing control and fuel delivery can be affected, which isn’t great for safety or the catalytic converter. Best bet is to have it diagnosed and sorted promptly.

Does the Impreza use both crank and cam sensors?
Yes. The ECM relies on the crank sensor for base engine speed/position and the cam sensors for phase information. Together they provide accurate timing for spark, fuelling, and variable valve timing. A fault in either can trigger hard starting or poor performance, but diagnostics will pinpoint which one’s playing up.