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

Updated: Jan 8

The crankshaft position sensor is an important component of your vehicle's engine management system. It is responsible for detecting the position of the crankshaft and sending this information to the engine control unit (ECU).


This information is used to control the ignition timing, fuel injection, and other functions of the engine.


In this article, we will discuss how to relearn a crankshaft position sensor and the importance of doing so after replacing the crankshaft position sensor.


Relearning a crankshaft position sensor is also known as CASE (Crank Angle Sensor Error) relearn.
 

Table of Contents:


OBD scanner being used on a vehicle

Does a Crankshaft Sensor Have to Be Relearned?

In most cases, yes, a crankshaft position sensor must be relearned after it has been replaced. This is because the ECU stores information about the sensor's position and characteristics, and this information must be updated when the sensor is replaced.


If the sensor is not relearned, the engine may not run correctly and may even stall.


What Happens if You Don’t Relearn Crankshaft Position Sensor?

If you do not relearn a crankshaft position sensor after replacing it, the engine may not run correctly. This can result in poor performance, reduced fuel efficiency, and possibly even engine damage. In some cases, the engine may stall or fail to start.


> Learn more about what happens if you don't relearn a crankshaft sensor


How to Relearn Crankshaft Position Sensor

The process of relearning a crankshaft position sensor varies depending on the make and model of your vehicle. Below are the general steps to follow when you relearn a crankshaft position sensor using a diagnostic tool.


  1. Consult your vehicle's service manual for specific instructions on relearning the crankshaft position sensor.

  2. Connect an advanced diagnostic scanner to your vehicle's OBD port. This will allow you to access the ECU and perform the relearn procedure.

  3. Follow the instructions on the scanner to initiate the relearn procedure. This may involve turning the ignition on and off, starting the engine, and performing other actions.

  4. If the relearn procedure is successful, the scanner will display a message indicating that the sensor has been relearned.

  5. Disconnect the scanner and test the engine to ensure that it is running correctly.


How to Relearn a Crank Sensor Without a Scanner

If you do not have access to a diagnostic scanner, you may be able to relearn the crankshaft position sensor using the following method.


  1. Consult your vehicle's service manual for specific instructions on relearning the crankshaft position sensor.

  2. Disconnect the battery to reset the ECU.

  3. Reconnect the battery and start the engine.

  4. Allow the engine to idle for a few minutes.

  5. Turn the engine off and wait for at least 10 seconds.

  6. Repeat steps 3-5 two more times.

  7. Test the engine to ensure that it is running correctly.


This method may not work for all vehicles, so it is always best to consult your service manual or a mechanic for specific instructions.


Second Method

If the crankshaft position relearn procedure above didn't work you can try the second method below.


  1. Turn off all accessories, such as the radio and air conditioning.

  2. Start the engine and let it idle in park or neutral mode for two minutes.

  3. Slowly accelerate the vehicle to 55 mph at part throttle and maintain this speed for 8-10 minutes, or until the engine reaches operating temperature.

  4. Cruise at 55 mph for another 5-6 minutes.

  5. Slowly release the accelerator pedal to decelerate the vehicle to 45 mph without using the brake pedal. Maintain this speed for one more minute.

  6. Perform four deceleration cycles of 25 seconds each at a speed of your choice, returning to 45 mph for 15 seconds after each cycle. Do not use the brake pedal during this process.

  7. Accelerate to 55 mph and maintain this speed for 2 minutes.

  8. Stop the vehicle and let the engine idle with the transmission in neutral (manual gearbox) or park mode (automatic gearbox) for two minutes with both the brake and clutch pedals fully pressed.


Once you have completed these steps, the crankshaft relearn procedure should be complete. Make sure to follow the instructions carefully to ensure that the procedure is performed correctly.


Why Is My New Crankshaft Position Sensor Not Working?

There are several reasons why a new crankshaft position sensor may not be working correctly. Here are a few common causes.


  1. The sensor was not installed correctly. Make sure that the sensor is properly aligned and tightened in place.

  2. The sensor is defective. In rare cases, the sensor may be faulty out of the box.

  3. The wiring is damaged. Check the wiring for any visible signs of damage, such as frayed wires or broken connectors.

  4. The ECU is not programmed correctly. If the ECU has not been properly programmed to recognise the new sensor, it may not be able to properly interpret the information being sent by the sensor.


If you have followed the correct steps for installing and relearning the crankshaft position sensor, and it is still not working correctly, you may need to diagnose and troubleshoot the problem further.


This may involve checking for fault codes with a diagnostic scanner, inspecting the wiring and connections, or checking for other issues with the engine management system.


It is always a good idea to consult a mechanic or refer to your service manual for assistance with diagnosing and fixing problems with your vehicle's crankshaft position sensor.


Conclusion

The crankshaft position sensor is an important component of your vehicle's engine management system. If you need to replace the sensor, it is essential to relearn it so that the ECU can properly recognize and interpret the information being sent by the sensor.