Car won’t start after replacing crankshaft position sensor. Here’s why

That’s no major issue because, with a little knowledge that entails understanding the role of the sensor, you can quickly resolve it.

Care to know why the car won’t start after replacing the crankshaft position sensor? If yes, here’s the answer:

It could be that the crankshaft position sensor was installed incorrectly or the installation created another issue that is preventing the engine from starting.

More About The Possible Causes of this Problem

1. An Incorrectly Installed Crankshaft Position Sensor

If your crankshaft position sensor is not installed correctly, the electrical sensor will not work. That means it won’t monitor the crankshaft’s position.

Consequently, the ECM unit won’t know the correct position of the crankshaft or cylinders since it isn’t receiving this information from the sensor.

This will cause the computer to fail at optimizing the timing of fuel injection into the cylinders so that the engine can start. Meaning the engine won’t start.

The good news is that you can use the OBDII scanner to check whether or not the sensor is installed correctly.

2. The Installation Created Another Issue In the Engine

It’s possible to damage the components that play a role when it comes to starting the engine. These components include the ignition switch, ECM, starter solenoid or relay, and starter motor.

If any of them stops working as a result of the damage, you can be sure that the engine won’t start. The good news is that you can use the OBDII scanner to check for any component of the ignition system that you may have damaged when installing the sensor.

How Can You Fix a Car That Won’t Start After a Crankshaft Is Replaced?

  • By re-installing the crankshaft position sensor correctly if it’s installed incorrectly.
  • By fixing any problem preventing the engine from starting, which might have been created by installing the crankshaft position sensor.
  • Resetting the new crankshaft position sensor.
  • Disconnecting and then reconnecting your battery.

Does Resetting the New Crankshaft Position Sensor Fix This Issue?

The short answer is yes. The crankshaft position sensor monitors the crankshaft spinning rate and sends that information to the ECM in real-time. The computer then times and injects fuel into the combustion chamber as necessary to start the car.

Please note that the engine will start and generate the right power only when the sensor is in harmony with the electronic control module.

Luckily, there are many ways to make the sensor and the ECM work in sync. Resetting the sensor or the computer are just some of them.

The easiest way to do that is to use your OBD2 scanner if it has a crankshaft sensor relearn function. Now, OBD2 scanners with crankshaft position sensor relearn are different.

That means that the relearn procedure will vary from one model to another, even though it’s simple across the board. Having said that, just follow the simple on-screen instructions provided by your scanner to quickly reset your position sensor.

Will Disconnecting the Battery Fix This Problem?

In some cases yes, because this practice resets the ECU, allowing it to function in sync with the crankshaft position sensor. Don’t forget that for the car to start, both components must work in harmony.

To disconnect the battery, start by removing the negative cable from it followed by the positive one. To reconnect it, begin by connecting the positive cable to it and then the negative one.


The crankshaft position sensor plays an important role in the functioning of your engine. This electrical sensor monitors the position and rotation speeds of your crankshaft.

It then sends this data to the ECM, which uses the information to calculate the right amount of fuel that needs to be injected into the cylinders to start the engine.

If the engine can’t seem to start after replacing the crankshaft position sensor, the two likely culprits are; how the sensor is installed and the installation process.

If the sensor is installed incorrectly, the car will not start. If the installation process caused serious damage to a component that is vital to the engine starting process, causing it to cease functioning, again, the car won’t start.

Fortunately, you can fix this issue by reinstalling the sensor correctly, resetting the ECM, disconnecting and reconnecting the battery, or fixing the damaged component.

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