Parts for your 2013 Mazda 3-Camshaft sensor

2013 Mazda 3 camshaft sensor — what it does, when it fails, and how to sort it

Yes, the 2013 Mazda 3 is fitted with a camshaft position sensor (often called a CMP sensor). Technical sources that detail this include the Mazda 3 (BL) Workshop Manual under Engine Control — Camshaft Position (CMP) Sensor, Mazda Electronic Service Information wiring diagrams for the 2010–2013 BL series, and Mazda parts catalogues listing CMP sensors for both the MZR 2.0/2.5 and SKYACTIV‑G 2.0 engines. These documents show the PCM relies on both crank and cam sensors for sequential fuel injection, variable valve timing control, and misfire monitoring.

On this Mazda 3, the camshaft sensor tells the engine computer exactly where the cam is, so it can fire the injectors and ignition at the right moment and manage VVT properly. When it’s healthy, starts are crisp, fuel economy stays tidy, and the engine feels smooth across the rev range. When it’s crook, the car can be a pig to start, run rough, lose power, and light the MIL with codes like P0340 or P0341.

There’s no scheduled replacement for the sensor itself — it’s a solid‑state, no‑service item — but it should be checked during routine servicing if there are hard starting complaints, intermittent stalling, or cam/crank correlation fault codes. A smart check includes inspecting the harness for chafing, making sure the connector is clean and oil‑free, and confirming the sensor has a good power, ground, and signal with a scope if available.

Replacement is straightforward for most engines fitted to the 2013 Mazda 3. It’s typically mounted on the cylinder head near the cam cover. Usual steps are: disconnect the battery, unplug the connector, remove the retaining bolt, ease the sensor out (there’s an O‑ring), lightly oil the new O‑ring, install the new unit, and tighten to the workshop‑manual torque spec. Clear codes and perform a test drive, a special “relearn” is rarely needed as the PCM adapts once it sees a clean signal.

Use a quality OEM or reputable aftermarket part — cheap knock‑offs can cause ghost faults. If there’s engine oil in the connector, track down any cam cover or VVT solenoid leaks first, otherwise the new sensor can be contaminated again. Most workshops will allow about half an hour for the job, give or take.

• Typical symptoms: long crank, rough idle, flat spots, poor economy, MIL with P0340/P0341
• Good practice: check wiring, connectors, and related oil leaks before condemning the sensor
• After fitment: clear DTCs, road test, and verify cam/crank sync data

Technical references named: Mazda 3 (BL) Workshop Manual — Engine Control System (CMP Sensor), Mazda ESI wiring diagrams (2010–2013 BL), Mazda Global Parts Catalogue for MZR and SKYACTIV‑G CMP sensors, professional data services such as Autodata/ALLDATA listing DTCs P0340/P0341 for this model.

FAQs

Where is the camshaft sensor on a 2013 Mazda 3?
It’s mounted on the cylinder head near the cam cover. On MZR engines it sits toward the front/side of the head, on SKYACTIV‑G it’s also at the head with easy access from above. Look for a small two‑or‑three‑wire sensor held by a single bolt.

What are the common signs it’s failing?
Long cranking, rough idle, hesitation, limp behaviour, and the MIL on with codes like P0340/P0341. If those show up, always check the plug and wiring before replacing the sensor.

Do I need a relearn after replacing it?
Generally no. Clear any codes and take a decent drive cycle. The PCM will recognise the new clean signal on its own. If issues persist, recheck wiring and confirm crank sensor health too.