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How to Relearn the Crankshaft Position Sensor (Step-by-Step)

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Last Updated on: 16th November 2023, 01:50 am

The crankshaft position sensor plays a vital role in your car’s engine management system. Its job is to detect the crankshaft’s position and send this data to the engine control unit (ECU).

The ECU uses this information to regulate ignition timing, fuel injection, and various other engine functions.

Usually relearning this sensor requires the use of an OBD scan tool but there is also a method without needing to use an OBD tool, which we’ll discuss further down.

Relearning a crankshaft position sensor is sometimes referred to as CASE (Crank Angle Sensor Error) relearn.

In this article, we’ll see how to relearn a crankshaft position sensor and understand why it’s crucial to do so after replacing the sensor.

Does a Crankshaft Sensor Need to Be Relearned?

Generally, it is necessary to relearn a crankshaft position sensor after replacing it.

This is because the engine control unit (ECU) retains data regarding the sensor’s position and characteristics, which must be updated when the sensor is changed.

Neglecting to relearn the sensor can lead to engine malfunctions and potential stalling.

crankshaft position sensor diagram

Failing to Relearn

If you fail to relearn a crankshaft position sensor following replacement, your engine’s performance may suffer.

This could result in subpar operation, decreased fuel efficiency, and even possible damage to the engine. In certain instances, the engine might stall or struggle to start.

How to Relearn a Crankshaft Position Sensor

The method for relearning a crankshaft position sensor can differ based on the specific make and model of your vehicle.

However, below are some general steps to follow when using a diagnostic tool for the relearning process.

  1. Connect an advanced diagnostic scanner to the OBD port of your vehicle. This connection will enable you to access the ECU and carry out the relearn procedure.
  2. Follow the instructions provided on the scanner to initiate the relearn process. This might involve actions like turning the ignition on and off, starting the engine, or performing other required steps.
  3. If the relearn procedure is successful, the scanner will display a message confirming that the sensor has been relearned.
  4. Disconnect the scanner and conduct an engine test to ensure that it is operating correctly.

To gain a visual understanding of how to relearn the crankshaft sensor, refer to the video below.

YouTube video

How to Relearn Without an OBD Tool

If you don’t have a diagnostic scanner at your disposal, there is an alternative method you can try to relearn the crankshaft position sensor.

Please note that this approach may not be effective for all vehicles, so it’s advisable to consult your vehicle’s manual or seek assistance from a mechanic.

Below are the steps for relearning the crankshaft position sensor using this method.

  1. Disconnect the battery to reset the engine control unit (ECU).
  2. Reconnect the battery and start the engine.
  3. Allow the engine to idle for a few minutes.
  4. Turn off the engine and wait for at least 10 seconds.
  5. Repeat steps 3 to 5 two more times.
  6. Test the engine to ensure that it is running correctly.

Remember, the success of this method can vary depending on the vehicle, so it’s always wise to refer to your vehicle’s manual or seek professional guidance when in doubt.

Second Method

If the previous crankshaft position relearn procedure didn’t yield the desired results, you can attempt the following alternative method. Please adhere to the instructions carefully to ensure a proper execution.

  1. Turn off all accessories, including the radio and air conditioning.
  2. Start the engine and let it idle in either park or neutral mode for a duration of two minutes.
  3. Gradually accelerate the vehicle to a speed of 55 mph while maintaining a partial throttle position. Sustain this speed for a period of 8-10 minutes or until the engine reaches its operating temperature.
  4. Cruise at a constant speed of 55 mph for an additional 5-6 minutes.
  5. Gradually release the accelerator pedal to decelerate the vehicle to a speed of 45 mph without utilizing the brake pedal. Keep the vehicle at this speed for one more minute.
  6. Execute four deceleration cycles, each lasting 25 seconds, at a speed of your choice. After each cycle, return to a speed of 45 mph for a duration of 15 seconds. It’s important not to engage the brake pedal during this process.
  7. Accelerate to 55 mph and maintain this speed for 2 minutes.
  8. Bring the vehicle to a stop and let the engine idle with the transmission in neutral (for manual gearbox) or park mode (for automatic gearbox) for two minutes. During this time, press both the brake and clutch pedals fully if applicable.

Upon completion of these steps, the crankshaft relearn procedure should be concluded. Remember to closely follow the instructions to ensure proper execution.

Why a New Sensor Isn’t Working

There are multiple potential reasons why a newly installed crankshaft position sensor might not function properly. Below are a few common causes to consider.

  1. Incorrect installation: Ensure that the sensor is accurately aligned and securely fastened in its designated position.
  2. Defective sensor: Although uncommon, there is a possibility that the sensor may be faulty right from the start.
  3. Damaged wiring: Inspect the wiring for visible signs of damage, such as frayed wires or broken connectors.
  4. Improper ECU programming: If the ECU has not been correctly programmed to recognize the new sensor, it may struggle to interpret the data provided by the sensor effectively.

If you have followed the appropriate steps for installation and relearning the crankshaft position sensor, and it still fails to function correctly, it may be necessary to conduct further diagnostic and troubleshooting procedures.

This may involve utilising a diagnostic scanner to check for fault codes, examining the wiring and connections, or investigating other potential issues with the engine management system.


The crankshaft position sensor holds significant importance in your vehicle’s engine management system.

When replacing this sensor, it is crucial to relearn it, allowing the ECU to accurately recognize and interpret the data transmitted by the sensor.

The relearning process for a crankshaft position sensor may differ based on the specific make and model of your vehicle.

However, it typically involves utilizing a diagnostic scanner and following specific instructions.

Alternatively, you can also learn how to relearn the crankshaft position sensor without the use of a scanner by following the method outlined in this article.

If you encounter difficulties with your newly installed crankshaft position sensor, it may be necessary to further diagnose and troubleshoot the problem.

  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer. He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

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