Engine Sensors
Engine sensors measure conditions such as crankshaft position, camshaft position, air flow, temperature and oxygen content, and report them to the ECU so it can control fuelling and ignition.
What it does
Each sensor converts a physical condition into an electrical signal. The ECU uses those signals to decide injector timing, ignition timing and fuelling. A sensor giving implausible data will cause the ECU to run a default strategy.
Signs a engine sensor is failing
- The engine warning light with a related fault code
- A vehicle that cranks but will not start, often a crankshaft position sensor
- Rough idle, hesitation or stalling
- Poor fuel consumption with no other symptom
- Intermittent cutting out that clears after the engine cools
When to replace them
Not scheduled. Replaced on failure. Crankshaft and camshaft position sensors are the most commonly needed same-day electrical lines.
What to confirm before ordering
Have these ready and the counter can usually confirm the part in under a minute.
- The exact sensor and its location, since engines carry several similar-looking sensors
- Connector type and pin count
- Engine code, because sensors differ across engine families
- That the wiring and connector have been checked before condemning the sensor
Engine Sensors by vehicle
Pick your vehicle for the years and engines covered, and what is specific to that application.
Engine Sensors questions
My fault code names a sensor. Is the sensor definitely faulty?
No. The code identifies the circuit reporting implausible data, which includes the wiring, connector and ECU input. Inspect the connector for corrosion and the loom for chafing before replacing the sensor.
Why will the engine not start when the crankshaft sensor fails?
The ECU uses crankshaft position to time ignition and injection. Without that signal it does not know where the pistons are, so it will not fire the injectors or coils at all.