Parts for your 2025 Mazda 3-Crank angle sensor

2025 Mazda 3 crank-angle sensor: fitted, important, and worth looking after

Based on Mazda service literature for the BP-series Mazda3 (2019–2025) and Mazda’s Electronic Parts Catalogue, a crankshaft position sensor (commonly called a crank-angle sensor) is fitted to the 2025 Mazda 3 with the 2.5L Skyactiv-G engines. Mazda’s diagnostic coverage includes DTCs P0335/P0336 for this sensor. So yes—this part is used and very relevant on the 2025 Mazda 3.

On the 2025 Mazda 3, the crank-angle sensor tells the ECU exactly where the crankshaft is and how fast it’s spinning. That precise angle and speed data lets the ECU trigger spark and fuel injection at the right moment, coordinate variable valve timing, detect misfires, and get the engine started cleanly and reliably. It reads a toothed wheel on the crank, producing a clean signal the ECU can trust at idle, wide-open throttle, and everything in between.

It isn’t a scheduled service item, but it’s smart to keep an eye on it during regular servicing—mainly the wiring and connector under the bonnet. Heat, oil weep, or road grime can affect the plug or loom over time. If faults do occur, they usually show up as:

• Long cranking or a no-start when hot or cold
• Intermittent stalling or cutting out while driving
• Rough running with erratic tachometer behaviour
• Check engine light with codes like P0335/P0336

Basic checks before replacing the sensor include confirming battery health, inspecting the harness for rub-through or oil contamination, ensuring the connector pins are clean and snug, and verifying engine and body earths. A scan tool can show engine speed while cranking—if it reads zero, that often points to a crank-angle sensor or its wiring. An oscilloscope gives the best view of signal quality, but most workshops will diagnose it with scan data and continuity checks.

When replacement is needed, a quality OEM-equivalent or Mazda Genuine sensor is the way to go. The unit is typically held by a single fastener and sealed with an O-ring. Standard fitment steps are to disconnect the battery negative, gain access (from above or below, depending on tools), unclip the connector, remove the fastener, and withdraw the sensor. Lightly oil the new O-ring, seat the sensor cleanly, route the loom exactly as factory, and tighten to the workshop manual torque. Clear fault codes, perform an idle relearn if required, and road test. Most jobs land around 0.5–1.0 hour depending on access.

There’s no adjustment on this sensor—the air gap is fixed by design—so correct installation and clean mating surfaces are key. Avoid pressure-washing the area and keep magnetic debris away from the sensor tip to help it live a long life.

Popular questions

Where is the crank-angle sensor on a 2025 Mazda 3?
It’s mounted on the engine, reading a toothed wheel on the crankshaft. Depending on variant and access, it’s typically reached from the front or the transmission side. A quick look under the bonnet or a glance in the workshop manual will point to the exact spot on the BP-series engine.

Do crank-angle sensors need routine replacement?
No, they’re not a consumable. They’re usually replaced only when faulty. Good practice is to inspect the connector, loom routing, and nearby oil leaks during regular services, as those are the things that tend to cause issues over time.

Is it safe to drive with a failing crank-angle sensor?
It may run, then suddenly stall or refuse to restart—so it’s not ideal or safe. If there are symptoms or related fault codes, it’s best to get it diagnosed and sorted promptly to avoid being stranded.