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How to Start a Car With a Bad Crankshaft Sensor (Step-by-Step)

Updated: Jan 9

An important component that is essential for starting a vehicle is the crankshaft position sensor (CKP).


This sensor plays a vital role in the proper functioning of the engine, as it helps to monitor the position and rotational speed of the crankshaft.


If the crankshaft sensor is not functioning properly, it can cause a range of issues that may make it difficult or impossible to start the car. In this article, we will explore how to start a car with a bad crankshaft sensor.

 

Table of Contents:

 

What Is a Crankshaft Position Sensor?

A crankshaft position sensor, also known as a crank sensor, is a device that is used to monitor the position and speed of the crankshaft.


The crankshaft is a central component of an engine, as it converts the linear motion of the pistons into rotational motion, which is then used to power the vehicle.


The crankshaft position sensor is typically located near the crankshaft, and it works by sending electrical signals to the engine control unit (ECU) when the crankshaft is turning.


The engine control unit (ECU) uses this data to regulate the timing of the ignition system, fuel injection, and other engine functions. The crankshaft position sensor, when combined with the camshaft position sensor, enables the engine to be completely in sync and run smoothly.


diagram showing how a crankshaft position sensor works

Where Is the Crank Sensor Located?

The crankshaft position sensor is typically located near the crankshaft, either on the engine block or on the transmission.


In most vehicles, it is located on the engine block, and it is usually located on the front of the engine near the bottom.


Some vehicles may have the sensor located on the transmission, in which case it will typically be found on the side or near the bottom of the transmission.


a crankshaft position sensor outlined with a red circle showing its location

Signs of a Faulty Crankshaft Sensor

There are several signs of a faulty crankshaft sensor that may indicate that the sensor is not functioning properly. These signs may include the following.


  1. Engine misfiring: If the crankshaft position sensor is not working correctly, it may cause the engine to misfire and run poorly.

  2. Check engine light: The check engine light may come on if the crankshaft sensor is not functioning properly.

  3. Reduced fuel efficiency: A faulty crankshaft position sensor may cause the engine to run poorly, which can lead to reduced fuel efficiency.

  4. Difficulty starting the car: If the crankshaft sensor is not working correctly, it may be difficult or impossible to start the car.

  5. Stalling: If the vehicle has a bad crankshaft sensor the vehicle may unexpectedly stall while driving or idling.

  6. Rough idle: The vehicle may have a rough idle (vibrations, fluctuating RPMs, etc.).


What Happens When a Crank Sensor Goes Bad?

When a crankshaft position sensor goes bad, it can cause a range of issues that may affect the performance of the engine and the ability to start the car.


Because the crankshaft sensor provides vital information to the ECU about the position and speed of the crankshaft, if the crank sensor is faulty it can cause the engine to go out of sync and run poorly, or not run at all.


Some of the potential issues that may occur with a crankshaft sensor failure include the following.


  1. Engine misfiring: If the crankshaft sensor is not functioning properly, it may cause the engine to misfire or run poorly. This can lead to reduced performance and fuel efficiency, as well as increased emissions. This could also lead to engine knocking.

  2. Difficulty starting the car: A faulty crankshaft sensor may make it difficult or impossible to start the car. This is because the sensor is responsible for sending electrical signals to the ECU to indicate the position and speed of the crankshaft, which is necessary for proper ignition timing and fuel injection. Without these signals, the engine may not start or may have starting problems (starts and then quickly stalls).

  3. Damage to the engine: If the crankshaft sensor is not functioning properly, it may cause damage to the engine over time. This is because the sensor is responsible for tracking the speed and location of the crankshaft, ensuring the engine is running in sync. If the sensor goes bad it could result in timing issues and knocking, resulting in engine damage.


Can a Car Start With a Bad Crankshaft Sensor?

In most cases, a car will not start if the crankshaft sensor is not functioning. This is because the sensor is responsible for sending electrical signals to the ECU to indicate the position and speed of the crankshaft, which is necessary for proper ignition timing and fuel injection.


Without these signals, the engine may not start or may start and then quickly stall. However, it is possible that a car may start with a bad crankshaft sensor in certain circumstances.


For example, if the sensor is only partially malfunctioning, it may still be able to provide some signals to the ECU, which may allow the car to start and run for a short period of time.


In these cases, the car may start and then quickly stall, or it may run poorly and experience reduced performance and fuel efficiency.


How to Start a Car With a Bad Crankshaft Sensor

If you are having difficulty starting your car and suspect that the crankshaft sensor may be the cause, there are a few things you can try to get the car started.


You could first try to temporarily fix the crankshaft sensor by following the steps below.