What Causes Crankshaft Sensor to Go Bad?

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A crankshaft sensor is a component found in modern vehicles that helps the engine control module (ECM) to determine the rotational speed and position of the crankshaft. It is usually located near the crankshaft, usually near the crankshaft pulley or flywheel, and is responsible for sending signals to the ECM, which then uses the information to control the fuel injection and spark timing of the engine. In other words, it helps the ECM to monitor engine power, performance, and fuel economy.

Common Causes of a Crankshaft Sensor Going Bad

Common Causes of a Crankshaft Sensor Going Bad can range from loose wiring or connection to being exposed to too much heat. With modern vehicles, the most common cause is a faulty Engine Control Module (ECM), which is responsible for controlling the fuel injection and spark timing. Other common causes include a build up of dirt or oil on the Crankshaft Position Sensor or CPS. This can cause interference with the fuel injectors and rotational speed of the crankshaft, leading to trouble codes and a check engine light. Other causes can include a bad spark plug, fouled fuel injectors, or a worn-out crank sensor.

Signs and Symptoms of a Bad Crankshaft Sensor

When it comes to determining if your crankshaft sensor is bad, there are a few signs and symptoms to look for. Common symptoms of a bad crankshaft sensor include poor fuel economy, engine power loss, stalling, and a check engine light on your dashboard. Additionally, your engine might have rough idling, difficulties when starting the engine, and a constant speed of the engine even when the accelerator isn’t engaged. All of these symptoms can lead to expensive repairs if not addressed in a timely manner. In a modern vehicle, the crankshaft sensor is essential for proper functioning, as it helps control the fuel injectors, engine timing, and other important aspects of engine operation.

Diagnosing and Testing a Bad Crankshaft Sensor

When it comes to diagnosing and testing a bad crankshaft sensor, it’s important to know what you’re looking for. If your car’s engine control module (ECM) detects problems with the sensor, it will typically trigger a “Check Engine” light. This is a common symptom of a bad crankshaft sensor, but it’s not the only one. Other common signs include fuel injection problems, engine power loss, rough idling, and spark timing issues. To diagnose the problem, you’ll need to identify the trouble codes stored in the ECM and then use a specialized scan tool to measure the crankshaft position sensor’s rotational speed. This will help determine if the sensor is functioning correctly or not. If the scan tool detects a problem, you may need to replace the crankshaft sensor. This can be expensive, so it’s best to diagnose the problem before replacing the sensor. To test the sensor, you’ll need to measure its pulses at a constant speed, as well as its ability to accurately trigger the fuel injectors. Finally, you’ll also need to check any loose wiring that could be causing the problem. If all else fails, it’s best to take your vehicle to an experienced mechanic for a proper diagnosis and repair.

shiny car crankshaft engine motor

Repairing or Replacing a Crankshaft Sensor

Repairing or Replacing a Crankshaft Sensor is a job best handled by an experienced mechanic. If the sensor is malfunctioning, the technician will first check for any loose wires or connections to ensure proper functioning. If the issue is not caused by a loose connection, the mechanic will then proceed to replace the sensor. Replacing a crankshaft sensor is a relatively simple job, but it does require specialized tools and knowledge of the car’s specific make and model.

When replacing the crankshaft sensor, it is important to use parts specifically designed for your car. Using generic parts can lead to problems down the road, as they may not be compatible with the car’s engine control module.

Once the new crankshaft sensor is installed, the mechanic will then test it to see if the check engine light has gone off. If the light is still on, they may need to run a few more tests to identify the root cause of the problem. It is important to have a mechanic check the fuel injection system and spark timing, as these can affect the crankshaft sensor’s performance.

It is important to note that replacing a crankshaft sensor can be an expensive repair. That said, modern vehicles are designed to last longer and require fewer repairs. As such, investing in a new crankshaft sensor can help you avoid more expensive repairs in the future. This is especially true if you catch the warning signs early and replace the sensor before it fails.

Preventing a Crankshaft Sensor from Going Bad

Preventing a Crankshaft Sensor from Going Bad is the ideal outcome. As modern vehicles are increasingly reliant on their Crankshaft Sensors, it is important to pay attention to warning signs and perform routine maintenance to make sure it is in proper functioning condition. This includes checking for loose wiring, checking the engine control module, and watching for common signs like an illuminated check engine light. If warning signs are detected, an experienced mechanic should be consulted to diagnose and test the Crankshaft Sensor. Taking proactive steps to ensure a healthy Crankshaft Sensor can help avoid expensive repairs and ensure your vehicle has the proper fuel injection, rotational speed, spark timing, and engine power to keep it running smoothly.


When it comes to a crankshaft sensor going bad, the most important thing is to pay attention to the warning signs. If the engine control module notices any variation in the rotational speed of the engine, it will typically indicate a malfunction or bad crankshaft sensor by triggering a check engine light. Common symptoms of a bad crankshaft sensor are rough idling, misfiring, a decrease in engine power, and difficulty starting the engine.

It’s also important to watch for common signs of a bad crankshaft sensor, such as improper fuel injection, spark timing, and trouble codes. A mechanic or experienced technician can diagnose and test the crankshaft sensor and see if it’s functioning properly or not.

If the crankshaft sensor is bad, the only option is to repair or replace it. This may be costly and expensive, depending on the year, make, and model of your car. In a modern vehicle, replacing the crankshaft position sensor can be quite complex and should only be done by a qualified and experienced mechanic.

In order to prevent a crankshaft sensor from going bad, it’s important to do routine maintenance and check for problems such as loose wiring or other issues that can affect the proper functioning of the sensor. Additionally, if the engine is having trouble idling at a constant speed, it’s important to check the crankshaft sensor and make sure it’s functioning properly.

In conclusion, a crankshaft sensor is an important component of the vehicle’s engine and should be checked and maintained routinely. If a crankshaft sensor is malfunctioning, it can cause serious problems and expensive repairs. Pay attention to the symptoms and warning signs of a bad crankshaft sensor and take your vehicle to an experienced mechanic if you notice any of these signs. With proper maintenance and care, you can avoid expensive repairs and have a safe and reliable vehicle.