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What Happens if You Don’t Relearn a Crankshaft Position Sensor? (Explained)

Updated: Jan 9

The crankshaft position sensor informs the engine control unit (ECU) of where the crankshaft is, this ensures the engine is in sync (ignition timing, fuel injection, etc.). If this sensor fails, it leads to a slew of issues. It is advised that the crankshaft position sensor be relearned if it's replaced.

If the crankshaft position sensor is not relearned, the ECU may not know the position of the crankshaft. This can cause issues like that of a faulty sensor, such as a poorly running engine, stalling, failing to start, increased vibrations, and may result in engine damage.

The process of relearning the crankshaft sensor is relatively simple and takes less than 30 minutes. To relearn the sensor, you'll need a professional OBD tool that can interface with the ECU. The procedure is simple, requiring just that you follow the directions on the screen.


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OBD scanner being used in a vehicle

When You Should Relearn a Crankshaft Position Sensor

This sensor functioning correctly is essential for the engine to work properly. You may need to relearn a crankshaft sensor for the following reasons.

  • The crankshaft position sensor has been replaced

  • The ECU has been replaced

  • The battery has been replaced