What Happens If You Don’t Relearn Camshaft Position Sensor?

An accurate camshaft position sensor ensures that the camshaft sync with the crankshaft by measuring its speed and position. 

If you change your vehicle camshaft position sensor or other engine components, first, you need to relearn the sensor. 

Otherwise, it’ll fail to measure the accurate speed and position of the camshaft, which will cause several vehicle malfunctions. 

In the article, you will learn what happens if you don’t relearn the camshaft position sensor. Also, I will explain how you can relearn a camshaft position sensor.

What Happens If You Don't Relearn Camshaft Position Sensor

What is Camshaft Relearning?

Relearning refers to re-engineer, re-program, or re-calibrate the engine. If the Camshaft position sensor, engine, or timing cover is moved, removed, replaced, or disturbed, then the Camshaft position sensor needs to be relearned.

It is necessary to relearn the sensor to synchronize it with the Camshaft. The PCM uses this data for several purposes, such as determining ignition timing, identifying cylinder misfires, timing fuel injectors, etc.

The engine may still run without relearning, but the PCM will use the incorrect “sync” data from the last relearn.

What happens if you don’t relearn Camshaft position sensor?

The ECU uses the signal from the position sensor to calculate engine speed and ensure the spark plug fires at the right moment. So, if you don’t relearn the Camshaft position sensor, the ignition system will fail to operate correctly. 

Here are listed some common problems that happen with your vehicle if you don’t relearn Camshaft position sensor:

Engine won’t start

Without relearning, the ECU sometimes doesn’t get the accurate location of the Camshaft and engine speed.

The ignition will not maintain the correct timing of spark plug fires, which can affect the vehicle’s regular operation. The engine will not be able to start because of this obstacle.

Engine will overheat

The Camshaft position sensor maintains the engine and engine component’s temperature by combining working with the crankshaft sensor.

But, if you don’t relearn the system, the sensors will send misleading information about Camshaft rotation, which is excessive build-up. For this, the engine will face an overheating issue.

Engine misfire

You will notice an engine misfire if you do not relearn the Camshaft position sensor, as the sensor sends the ECU incorrect information. A misfire in your engine may cause it to stumble or even lose speed (RPMs).

Ignition problems

The camshaft position sensor collects the position and angle of the camshaft. Then, it sends the data to the ECU, which calculates the information and controls the ignition and fuel injection.

If you don’t relearn the sensor after replacing it, it might provide previously saved data to the ECU. The vehicle cannot ignite the spark so starting will be challenging. Also, you will notice an ignition misfire.

Rough acceleration

If your vehicle doesn’t get the proper information from the Camshaft position sensor, it cannot be able to adjust the spark timing or fuel injection. For this, your vehicle will face difficulty with a constant speed vehicle accelerating. You will notice uneven or rough acceleration.

Increase fuel consumption

The ECU and Camshaft position sensor work together to manage fuel injection. ECUs can inject too much or too little fuel if they receive inaccurate Camshaft location information. This will affect fuel efficiency. Also, it will increase the emission.

Advantage of relearning the Camshaft position sensor

After relearning the sensor, you will have a pleasant experience while driving your car. The relearn process ensures that ECU gets a proper signal from the Camshaft, which means no misfire, rough acceleration, and many more. 

You can enjoy the ride rather than thinking about stalling at the roadside. Also, this help to remove any remaining code that might cause your headache. 

How to relearn Camshaft position Sensor?

A Camshaft position sensor’s relearn procedure varies slightly according to the car’s model and make. But, you can follow the steps below to relearn the sensor applicable to almost all GMC vehicles.

Relearn Camshaft Position Sensor Using scanner

Step 1: First, turn on your vehicle’s ignition without starting the engine. This will help the scanner tool get the information from your vehicle properly.

Step 2: Now, connect an OBD2 scanner tool with your vehicle. For most vehicles, the OBD2 port is located near the front door of the driver’s seat.

Step 3: Select your vehicle type and model. Also, you can use the auto-detect option, which asks for your VIN. Put the VIN number, and it will collect the vehicle information.

Step 4: Go to the “Diagnose” function and then “control Unit.” In the next window, you will get different parts options of the vehicle. You need to go to the “Powertrain.” Then, select the “ECM – Engine Control Module.” 

Step 5: On the next window, you will get the “Special Function” option. Then go to the “Cam crank relearn.” Then the information tab will open, which informs you when you should relearn the Camshaft position sensor. 

Step 6: The scanner will ask you to turn on the engine. Then, turn on the engine. At this moment, your vehicle coolant temperature should be 70 degrees Celsius. Otherwise, you cannot perform the relearn process.

Step 7: If the required temperature reaches, it will show it’s in progress now. After completing the relearn process, it will show you the complete message on the scanner tool.

NOTE: If the scanner tool detects other error codes, you must first clear them. Otherwise, the relearn procedure cannot be done.

Relearn Camshaft Position Sensor Without Scanner Tool

Some vehicle models (some truck applications 1998 & later) relearn process cannot be done by a scanner tool. For this, you need to follow the manual method to do.

Here is a step-by-step process of how you can relearn the sensor without a scanner tool:

  • Turn off the vehicle’s other accessories and check the air and coolant temperature. 
  • Now, turn on the engine and keep it in the park or neutral mode for 2 minutes. 
  • To reach operating temperature, accelerate to 55 mph on part throttle. Then, cruise for 8-10 minutes at this speed.
  • Continue cruising at 55 mph for another 5 to 6 minutes.
  • Decrease the vehicle to 45 mph without pressing the brake pedal. Release the feet from the accelerator pedal and wait for one minute at this speed.
  • You need to perform four 25-second deceleration cycles at a speed of your choice, followed by 15 seconds of 45 mph. You should not step on the brake during this procedure.
  • Then again, speed up to 55 mph and maintain the speed for two minutes.
  • With the clutch pressed and the brake applied, stop the vehicle and idle it for two minutes.

NOTE: If your vehicle has poor scanner support, you can follow the above method. However, it will be a good decision to contact a professional if you cannot perform the relearn process using a scanner tool.


Do Camshaft sensors need to be relearned?

Yes, you need to relearn the Camshaft position sensor whenever you change the engine or engine component. You need to do the process to ensure the proper functionality of the Camshaft after changing parts.

Also, If you replaced the vehicle ECU, you need to relearn the sensor for appropriate communication with the new ECU.

Will disconnecting the battery reset the Camshaft sensor?

Removing the battery negative terminal for an hour can drain any remaining power or error code. But, most vehicles cannot reset the Camshaft position sensor.

You need to use a scanner tool to reset the Camshaft sensor. But, it will help to remove any remaining store code on the Camshaft position sensor.

How long does it take to relearn?

Anyone can do the relearn process if they own a good quality OBD2 scanner tool. The procedure is so easy, and you don’t need to have any mechanical knowledge to perform the task. The relearn procedure will not take more than 10 minutes.

How much does it cost to relearn from a mechanic?

The cost will vary according to your location and vehicle model. But, as the relearn process doesn’t require any extra parts except a scanner tool that a mechanic already owns, the mechanic will take only the labor cost. The cost will be no more than $50.


The camshaft position sensor ensures that the ECU gets accurate information to control other necessary components of the engine. Overtimes, it can defect for several reasons.

But, after changing it, if you don’t reset or relearn the camshaft position sensor, you might notice the same issues why you change it.

My today’s guide will help you to get rid of such a situation. As you already know, what happens if you don’t relearn the camshaft position sensor and an easy way to do the relearn process.

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