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

Even a novice understands the irreplaceable importance of crankshaft position sensors in a typical vehicle.

They help monitor engine speed, RPM, and ignition timing, ensuring your car always enjoys the best performance and operation.

That’s why it’s paid to take care of these devices and relearn them from time to time.

So what if you keep these sensors the way they are? What happens if you don’t relearn crankshaft position sensor

This article by Bryan’s Garage will discuss these questions in more detail, citing trustable sources and relevant facts.

Keep scrolling for more of our analyses! 

What Is A Crankshaft Position Sensor and How Does It Work?

What Happens If You Don't Relearn Crankshaft Position Sensor?

First of all, it’s crucial to understand what these sensors entail and how they work from the beginning.


In simpler terms, we can understand crankshafts as a road going through the middle of every piston in the car engine.

These roads also have large gears attached to each point, which rotate and turn all the driveshafts linked to all the wheels.

As the name suggested, these crankshaft sensors are designed to monitor the rotational speed and position of the crankshafts.

To successfully perform that task, they send all relevant info to the ECU (or engine control units).

After that, the ECU will use those data pieces to handle fuel injection and ignition timing, facilitating smooth runs.

How Does It Work?

As you can guess, the crankshaft sensors are a crucial element of the car’s ignition system.

In most models, they are placed in the engine’s front compartment, right next to the pulley. These sensors often have toothed reflectors or wheels, which pass over them once the crankshafts rotate.

Such procedures generate electrical signals that travel straight to your ECU. Next, the ECU relies on those signals to assess where the crankshaft is put and where each piston lies.

On another note, the engine speed (RPM) can also be calculated via these signs.

The system then uses these numbers to set up proper ignitions, ensuring every spark plug will fire in time and no off-beat firing can occur!

For more analysis on their functions and possible symptoms of failure, click here.

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

Not relearning your crankshaft sensors can overheat or stall the engine, bring troubles to the vehicle circuitry, and lead to uneven acceleration.

1. The Engine Will Become Overheated

As previously discussed, crankshaft position sensors are responsible for handling the engine temperature – as well as other compartments within it.

By illustration, they monitor the crankshaft rotational speed and its whereabouts by sending data to ECUs, which then utilize that information to make necessary adjustments.

So your engine will become overheated once the sensors fail to deliver data properly – due to excessive build-up.

Such issues inevitably cause major damage to your sensors as well, especially if they cause the plastic coverings to melt down.

2. Serious Problems With The Automobile Circuitry

Another dilemma that might arise from your refusal to relearn the sensors are technical problems with the car’s circuitry.

When the crankshaft sensors malfunction or do not work properly, they can cause faulty voltage that interrupts the process of sending signals to the ECUs, affecting the appropriateness of the entire system afterward.

3. Stalled Intermittent

If drivers don’t rec-calibrate or re-engineer the engines after they have been replaced, the vehicle might start to stall.

Sadly, failures to fix that issue can cause dangerous and detrimental problems/accidents for your cars.

For example, it can suddenly lose power when you are in the middle of a highway or city-street trip. You don’t need us to tell you how that unexpected mishap can even cost you your life!

4. Uneven Acceleration

Your driving experience will suffer from issues of uneven acceleration, as well. After all, as the ECU only receives wrong or bad signals, it will be unable to tweak the ignition timing or fuel injection properly.

As a result, drivers cannot maintain their consistent speed during acceleration. Instead, the car will either accelerate unevenly or with incessant shifting delays. How inconvenient!

What About The Advantages of Relearning These Sensors?

As so many terrible accidents can happen if you refuse to relearn them, we hope you understand the wonderful benefits that sensor-relearning can bring to your driving experience.

They Keep Drivers from Ignition Problems/Issues

By re-engineering your engines once they have tampered, the ECU signals can ensure your vehicle ignites the right way.

No longer will drivers be alarmed by sudden ignition timing dilemmas. Such a fresh start guarantees you can easily crank the engine without major difficulties!

The Overall Trip Will Be Pleasant and Uninterrupted

Replacing or fixing engines in the vehicle might be very time-consuming (and even costly) – which is particularly true for those unfamiliar with the car engine and its compartments like crankshaft sensors.

Nevertheless, suppose you are willing to learn how to relearn them or at least have professionals do it for you. The car can confidently hit the street with an uninterrupted and smooth operation.

In simpler terms, there’s no need to worry about cars that cannot start, bumpy wheels, or any issue that might cause the car to underperform.

How To Relearn Crankshaft Position Sensor?

How To Relearn Crankshaft Position Sensor?

This section focuses on how to relearn crankshaft position sensor without scanner and with a scanner. Let’s get started.

1. With A Scanner

The sensor-relearning procedure does not always stay fixed. How it transpires depends on different car models and makes. But overall, it should not be so challenging – even for beginners.

For those who are not confident in their skills, you can always turn to professionals instead to get things done quicker.

Step 1. Switch on the car ignitions without starting it. After all, once the sensor scanner has been connected, starting your car is not really necessary.

Igniting it is enough to kick-start the scanner and make it pick out important details.

Step 2. On your scanner, select vehicle type, car make, and model. Remember that every car model has its own recalibrating processes.

If you need clarification on the car model, consult professionals to identify it and have the system relearned.

Step 3. Select “Diagnostics functions”, then press the control units. As you do so, the units will display every relevant information about your vehicle.

Step 4. Choose the engine modules. Once clicking, various options will appear. Scroll and click “Special functions”. Under that segment, choose “crank relearn”.

Step 5. Ensure only this function is at play when the car crank and cam undergo replacement. In the relearn section, press “OK” to start relearning.

Step 6. Start the car again, ensuring its temperature reaches at least 70. If it cannot, restart again and again until you achieve that number.

Small Note: If your scanner tool discovers other errors, clear them all first. Otherwise, your relearning procedure will only fail.

2. Without A Scanner

In some models (1998 truck applications and later), the relearning process can be a bit intricate, which scanner tools cannot interfere with.

As a result, following manual methods is a must. This step-by-step guide will detail how to perform crankshaft relearn without scanner.

  • Turn off other accessories in the car. Check to confirm the coolant and air temp stays fixed.
  • Switch on the engines. Keep them in neutral or park mode for about two minutes.
  • Accelerate to 56 MPH on the part throttle to help the car reach operating temp. Cruise at that speed for about 8 to 10 minutes. (for older models, keep cruising for another 6 to 7 minutes afterward).
  • Decrease your vehicle to 40 MPH without brake pedal pressure. Release your foot from these accelerator pedals and wait at that speed for about one minute.
  • At whatever speed you choose, perform four deceleration cycles (each lasts 25 seconds), followed by a 45-mph cycle of 15 seconds. Again, do not step your foot on the brakes throughout this procedure.
  • Accelerate to 56 MPH and keep the car at that speed for another two minutes.
  • Lastly, with applied brakes and pressed clutches, stop your car and let it stay idle for a few minutes. And that’s it. You have performed crankshaft variation relearn without scan tool successfully!

Small Note: This method mostly applies to car models with poor/low-quality scanner support.

Otherwise, if your car supports scanners – but for some reason, the scanner still fails to cooperate – it’s best to contact professionals instead.


1. After Changing The Sensors, Do I Need To Reset The Car Computer, Too?

For some old models, yes. Only then will all the short-term memory get properly deleted.

We suggest you disconnect the batteries via their negative terminals and let the car sit still for about an hour or so.

After that, reconnect the battery. Such strategies will drain all electronic power and clear the data memory properly.

After that, you should ensure nothing goes wrong by running a few laps to test the car’s operation. In most cases, the vehicle will work normally, but if they don’t, contact repair services for more support.

2. Can I Clean The Sensors Only (Rather Than Relearning or Replacing Them)?

The answer depends on every situation, but we DO receive reports from customers that sometimes, cleaning the sensors off grime and dirt is enough to make them work.

That said, as they wear down over time, that is not a permanent solution. We still suggest you replace and relearn them from time to time to guarantee the car’s all-time optimal performance.


Do you have to relearn a crankshaft position sensor? And what happens if you don’t relearn crankshaft position sensor

Bryan believes this article has thoroughly discussed every relevant facet of this question.

While the procedure varies across models, the basic steps are well-covered, ensuring even novices can follow with ease!If you have more questions about crankshaft relearn symptoms, contact Bryan anytime.

Our support team is always ready to give you support!

Leave a Comment