Parts for your 2004 Subaru Impreza-Crank angle sensor

2004 Subaru Impreza crank-angle sensor (crankshaft position sensor): purpose, service tips, and FAQs

Yes, the 2004 Subaru Impreza is fitted with a crank-angle sensor – Subaru labels it the crankshaft position (CKP) sensor. This is confirmed by the Subaru 2004MY Impreza Factory Service Manual (STIS) under diagnostics for DTC P0335/P0336, by Subaru’s parts catalogues listing a CKP sensor for EJ-series engines used in 2004 models (EJ20/EJ25), and by aftermarket technical catalogues (e.g., NGK/NTK, Bosch) that specify a CKP sensor for this vehicle.

On this Impreza, the crank-angle sensor is critical to how the engine runs. It reads a toothed reluctor on the crankshaft and sends a precise speed and position signal to the ECU. The ECU then times spark and fuel injection to the millisecond, keeping cold starts smooth, throttle response crisp, and emissions in check. If the signal drops out, the engine can misfire, stall, or refuse to start altogether.

There isn’t a fixed replacement interval for the CKP on a 2004 Impreza, it’s generally “fit and forget”. That said, age, heat, and vibration can fatigue the sensor or its wiring. During regular servicing it’s sensible to scan for fault codes (P0335/P0336 are the big ones), inspect the connector and loom near the alternator and timing covers, and ensure the sensor mount is secure. The sensor itself sits on the top front of the engine block, tucked just behind the alternator, pointing at the crank sprocket’s reluctor.

Typical symptoms of a failing sensor include hot restarts being a pain, intermittent stalling at idle, a dead tachometer during crank, or random misfire codes. Because the sensor is non-contact, it doesn’t need cleaning, focus on clean, tight connections and intact wiring. For high‑kilometre cars that have lived a hot life, some workshops choose pre-emptive replacement as cheap insurance.

If replacement is needed, it’s a straightforward driveway job for a competent home mechanic, but many owners prefer a professional to verify timing signals and clear codes.

1. Disconnect the battery (under the bonnet) for safety and to avoid stored fault codes.
2. Unplug the CKP connector and remove the single retaining bolt.
3. Lift out the sensor, if the new unit has an O‑ring, lightly lubricate it before fitting.
4. Install the new sensor, tighten the bolt to factory spec (snug, not overtight), reconnect the plug, and reconnect the battery.

After replacement, a quick scan for codes and a short drive cycle will let the ECU relearn idle. No dramas if it briefly idles a touch high on first start.

Popular questions

What are the signs of a bad crank-angle sensor on a 2004 Subaru Impreza?
Common clues include intermittent no‑start when hot, sudden stalling at lights, rough running, a dead or jumpy tacho during cranking, and fault codes like P0335/P0336. The engine may crank strongly but not fire until it cools. Because symptoms can mimic a failing cam sensor or fuel issue, proper scanning and signal testing helps avoid parts darts.

Where is the crank-angle sensor located on a 2004 Impreza?
It’s mounted on the top front of the engine block, tucked behind the alternator under the bonnet, pointing at the crankshaft’s reluctor behind the front timing cover. It’s held by one small bolt and has a short two‑wire connector lead, making access reasonable once the alternator area is clear.

Does the crank-angle sensor need routine replacement?
There’s no scheduled interval. It’s replaced on condition—when fault codes or symptoms appear. On a high‑kilometre EJ engine, some workshops recommend proactive replacement during major front‑end servicing (e.g., timing belt work) because access is convenient and the part cost is modest, saving a potential roadside drama later.