What does the engine speed sensor do?New engine speed sensor Hamilton NZ

The engine speed sensor (or crankshaft sensor / crank angle senor) is used to detect how quickly your engine’s crankshaft is spinning. It then sends this data to your car’s onboard computer, which makes adjustments to your engine’s ignition timing and fuel injection to allow for optimum engine fuel economy, engine power, and exhaust emission conditions.

The engine speed sensor is mounted near to the engine’s crankshaft. Most engine speed sensors create a small magnetic field. When the crankshaft spins, its serrated edges obstruct the magnetic field. The frequency of obstructions determines how fast the crankshaft is moving.

As well as an engine speed sensor, most cars with auto transmissions will also have a transmission speed sensor, which monitors the rotations of your car’s transmission to change gears.

Problems with the engine speed sensor can affect the air/fuel ratio inside your engine. This can affect the performance and efficiency of the engine.
Learn more about air/fuel ratio >


Symptoms of a faulty engine speed sensor:

  1. Engine misfires: A malfunctioning engine speed sensor can cause misfires in one or more cylinders. You may experience a rough idle, hesitation, or stumbling during acceleration. The engine may also have a loss of power or a decrease in overall performance.
  2. Engine struggles to start: The engine speed sensor provides crucial information to the engine control unit (ECU) for proper fuel injection timing and ignition control. If the sensor is faulty, it may prevent the engine from starting altogether or make it difficult to start. You may have to engage the starter multiple times before the engine fires up.
  3. Stalling or sudden engine shutdown: A failing engine speed sensor can lead to intermittent stalling or sudden engine shutdown while driving. The sensor’s inaccurate or inconsistent signals to the ECU can disrupt the fuel injection and ignition timing, causing the engine to stall unexpectedly.
  4. Erratic or fluctuating tachometer reading: The engine speed sensor is responsible for providing the tachometer with accurate RPM information. If the sensor is faulty, the tachometer needle may behave erratically, jumping up and down or fluctuating even when the engine speed remains relatively constant.
  5. Increased fuel consumption: A malfunctioning engine speed sensor can disrupt the fuel injection process, leading to improper fuel-air mixture and inefficient combustion. This can result in increased fuel consumption and reduced fuel efficiency.
  6. Check Engine Light (CEL) illuminated: A faulty engine speed sensor often triggers the Check Engine Light on the dashboard. The ECU detects the irregular signals from the sensor and registers a fault code related to the engine speed sensor. Retrieving the trouble code using a diagnostic scanner can help identify the specific issue.
  7. Engine stalling or hard starting when hot – sometimes the engine speed sensor / crank angle sensor will fail when it is hot, which can cause the engine to stall or make it hard to start after the engine is hot. Sometimes just waiting for the engine to cool down will allow the engine speed sensor / crank angle sensor to start working again and the engine to start and run. In this situation the engine speed sensor / crank angle sensor will need to be replaced.


Engine Speed Sensor – Replacement in Hamilton

Is your car in need of a new engine speed sensor? If so, we can help! At Grimmer Motors, our team of skilled mechanics can quickly determine if the engine speed sensor is the cause of your engine’s running problems. If it is, we can install a new one for you. This will allow for reduced fuel consumption, optimum engine performance, reduced exhaust emissions and increased engine reliability.

For engine speed sensor / crankshaft sensor replacement and diagnostics in Hamilton, contact Grimmer Motors today!

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