Car Engine Won’t Turn Over

Causes

There are several reasons why a car engine might not turn over. Some of the most common causes include:

Dead battery: This is the most common cause of a car engine not turning over. If the battery is dead, there will not be enough power to turn the starter motor, which is what cranks the engine.
Bad starter motor: The starter motor is responsible for turning the engine over. If the starter motor is bad, it will not be able to turn the engine over, even if the battery is good.
Loose or corroded battery terminals: The battery terminals are what connect the battery to the starter motor. If the terminals are loose or corroded, they will not be able to conduct electricity properly, which will prevent the starter motor from turning the engine over.
Bad ignition switch: The ignition switch is responsible for sending power to the starter motor. If the ignition switch is bad, it will not be able to send power to the starter motor, which will prevent the engine from turning over.
Bad crankshaft position sensor: The crankshaft position sensor is responsible for telling the engine control unit (ECU) where the crankshaft is positioned. If the crankshaft position sensor is bad, the ECU will not be able to send the correct signals to the starter motor, which will prevent the engine from turning over.

Diagnosis

To diagnose the cause of a car engine not turning over, you will need to perform a few simple tests. These tests will help you determine which component is causing the problem.

Check the battery: The first thing you should do is check the battery. Make sure that the battery terminals are clean and tight. You can also use a voltmeter to test the battery voltage. If the battery voltage is below 12 volts, the battery is likely dead and will need to be replaced.
Check the starter motor: If the battery is good, the next thing you should do is check the starter motor. You can do this by tapping the starter motor with a hammer while someone else tries to start the engine. If the starter motor is bad, it will likely make a clicking sound when you tap it.
Check the battery terminals: The battery terminals are what connect the battery to the starter motor. If the terminals are loose or corroded, they will not be able to conduct electricity properly, which will prevent the starter motor from turning the engine over. To check the battery terminals, simply remove the nuts that hold the terminals in place and inspect the terminals for any damage or corrosion. If the terminals are damaged or corroded, they will need to be cleaned or replaced.
Check the ignition switch: The ignition switch is responsible for sending power to the starter motor. If the ignition switch is bad, it will not be able to send power to the starter motor, which will prevent the engine from turning over. To check the ignition switch, you will need to use a voltmeter to test the voltage at the starter motor. If there is no voltage at the starter motor, the ignition switch is likely bad and will need to be replaced.
Check the crankshaft position sensor: The crankshaft position sensor is responsible for telling the engine control unit (ECU) where the crankshaft is positioned. If the crankshaft position sensor is bad, the ECU will not be able to send the correct signals to the starter motor, which will prevent the engine from turning over. To check the crankshaft position sensor, you will need to use a scan tool to read the trouble codes from the ECU. If the trouble codes indicate that the crankshaft position sensor is bad, the sensor will need to be replaced.

Repair

Once you have diagnosed the cause of the problem, you can begin to repair it. The repair process will vary depending on the cause of the problem.

If the battery is dead, you will need to replace it.
If the starter motor is bad, you will need to replace it.
If the battery terminals are loose or corroded, you will need to clean or replace them.
If the ignition switch is bad, you will need to replace it.
If the crankshaft position sensor is bad, you will need to replace it.

Prevention

There are a few things you can do to help prevent your car engine from not turning over in the future. These include:

Keep your battery charged: Make sure that your battery is always charged. You can do this by driving your car regularly and by keeping the battery terminals clean and tight.
Get your car serviced regularly: Regular car servicing can help to identify and fix any potential problems before they become major issues. This includes checking the battery, starter motor, ignition switch, and crankshaft position sensor.
Park your car in a safe place: Parking your car in a safe place can help to protect it from damage. This includes parking your car in a garage or under a carport.

Conclusion

A car engine not turning over can be a frustrating experience. However, by following the steps outlined in this article, you can diagnose and repair the problem quickly and easily.