Your Selected Vehicle
Parts for your 2011 Subaru Impreza-Camshaft sensor
Explore 4WD & Adventure
2011 Subaru Impreza Camshaft Sensor — What It Does and How to Look After It
According to the 2011 Subaru Impreza Factory Service Manual (Engine Diagnostics), Subaru’s Technical Information System (STIS), and the official Subaru parts catalogue, the 2011 Impreza is fitted with camshaft position sensor(s). Naturally aspirated EJ-series engines use a cam sensor to determine cam phase for fuel and spark timing, while WRX/STI variants add a second sensor to support variable cam timing. So yes — this part is relevant on every 2011 Impreza.
The camshaft sensor feeds the ECU precise information about the cam’s position so it can fire injectors sequentially, trim ignition timing, and manage variable valve timing where fitted. That means quicker starts, smoother idle, cleaner emissions, and better fuel economy. When the sensor signal is dodgy, the ECU may fall back to guesswork, which can mean longer cranking, flat spots, poor fuel use, and a glowing check engine light with codes like P0340/P0341.
While the cam sensor isn’t a scheduled replacement item, it’s smart to keep an eye on it during regular servicing. Oil contamination at the connector, heat-soaked wiring, or a hard, flattened O-ring can all cause intermittent faults. Sticking to quality engine oil and on-time changes helps reduce metallic debris and varnish that can upset sensor readings.
- Common symptoms: hard starting, rough idle, hesitation off the line, reduced power, increased fuel use, and a check engine light (often with P0340/P0341).
- Location cues: mounted at the front of a cylinder head, naturally aspirated models typically have one sensor, WRX/STI models generally have one on each head.
- Best-practice replacement: use OEM or a reputable brand, replace the O-ring, check the harness for brittle insulation, clean the connector, and clear codes after fitting.
- Disconnect the battery and let the engine cool.
- Access the sensor on the cylinder head, unplug the connector, and remove the retaining bolt.
- Inspect and replace the O-ring, lightly oil it, fit the new sensor, and tighten to factory spec.
- Reconnect, clear fault codes, and verify a clean signal with a scan tool.
Whether it’s a daily 2.0/2.5-litre runabout or a WRX/STI, a healthy camshaft sensor keeps the Impreza starting first pop and pulling cleanly through the revs. If faults persist after replacement, check the crank sensor and timing belt/chain alignment, as the ECU needs all three to agree.
Popular questions
Where is the camshaft sensor on a 2011 Subaru Impreza?
On naturally aspirated EJ engines there’s typically one sensor mounted at the front of a cylinder head. WRX/STI models usually have one sensor on each head. It’s accessible from the front/top area of the engine, look for a small, two- or three‑pin connector going into a sensor held by a single bolt.
If access is tight, removing the intake snorkel or a cover can help. Always confirm with the vehicle’s engine section in the Factory Service Manual for your exact variant.
Can the car run with a bad camshaft sensor?
Sometimes, but not happily. The ECU may fall back to the crank sensor and batch-fire the injectors, which can mean long cranks, rough running, and increased fuel use. In some cases it won’t start at all. Driving like this can also trigger more fault codes and stress the catalytic converter.
Should the cam and crank sensors be replaced together?
Not by default. If diagnostics point to the cam sensor alone, just replace that. However, on higher‑kilometre cars with heat‑aged wiring and matching fault history, many techs prefer to test both and replace the pair if they’re the same age and showing similar patterns of interference or dropouts.
