Identifying the Symptoms of A Failed BMW Eccentric Shaft Sensor

The eccentric shaft sensor is not something every BMW owner knows about. Located deep inside the engine, the eccentric shaft sensor plays a key role in controlling the VALVETRONIC timing. If such an important sensor of your BMW fails, you will face all kinds of drivability problems; ranging from poor performance to starting trouble. Knowing when your vehicle's eccentric shaft sensor is about to fail can save you a lot of inconveniences.

This blog post covers everything you ever wanted to know about BMW’s eccentric shaft sensor, such as;

 Its location & purpose

 Reasons why this sensor may fail

 Recognizable signs of eccentric shaft sensor malfunction in BMW

Location & Purpose of Eccentric Shaft Sensor

The sole purpose of your BMW's eccentric shaft sensor is to monitor the rotation and position of the eccentric shaft. The eccentric shaft, by the way, is the part that plays a crucial role in the operation of your vehicle's VALVETRONIC system by adjusting the lift height of the valves. And, as far as the location of this sensor is concerned, you can find it attached to the cylinder head just below the valve cover of the engine.

Simply put, a properly functioning eccentric shaft sensor is essential to the smooth operation of your BMW's VALVETRONIC system. If for any reason the eccentric shaft sensor fails, your VALVETRONIC system will not be able to function properly. And, a faulty VALVETRONIC system can contribute to a range of problems such as poor engine performance, increased fuel consumption, higher exhaust emissions, etc.

The next topic that we will discuss in this blog post is the possible reasons that can result in ESS malfunction in BMW.

BMW Eccentric Shaft Sensor Failure: Reasons Explained

There are many different things that could contribute to eccentric shaft sensor failure in your BMW. Some of the most obvious ones are listed below. Please take a look;

 Electric short circuit

 Bad fuse or relay

 Damaged wire

 Aging

 Oil contamination etc…

Signs Your BMW Eccentric Shaft Sensor Has Malfunctioned

Sign #1- Engine lacks power

Since the VALVETRONIC system relies on eccentric shaft sensor data to dynamically adjust intake valve timing and duration; if the sensor wears out, the VALVETRONIC system will not function as it should. Its effect will be seen in the torque output of the engine. So, if you suspect that your BMW has been performing poorly of late, get its eccentric shaft sensor checked. If there is any defect in the sensor, get it replaced immediately.

Sign #2- Excessive fuel consumption

Has your BMW been consuming a lot of fuel lately? The cause could be a defective eccentric shaft sensor. BMW claims that the unique design of the VALVETRONIC system allows the engine to burn gas more efficiently (improves gas mileage by 10%). If there is something wrong with the eccentric shaft sensor, your BMW’s VALVETRONIC system will not function smoothly. As a result, you will notice a sudden jump in fuel consumption.

Sign #3- Excess exhaust emissions

Another common finding in a BMW with a faulty eccentric shaft sensor is increased exhaust emissions. The VALVETRONIC system works synchronously with various sensors to keep the air-to-fuel ratio properly balanced within the engine's combustion chamber. In the event that the eccentric shaft sensor wears out, the VALVETRONIC system will act up. As a result, the engine will run rich and produce a lot of emissions.

Sign #4- Engine warning light on

As with any engine-related problem, a faulty eccentric shaft sensor can result in the illumination of the check engine light. So, if your BMW is performing poorly, generating a lot of exhaust fume, and its check engine warning light is on, there is a good chance that its eccentric shaft sensor has malfunctioned. Only a mechanic will be able to tell what to do next after a thorough investigation.

To Be Brief…

The eccentric shaft sensor is an important part of your BMW’s VALVETRONIC system. If it malfunctions, you’ll encounter a wide range of problems ranging from sluggish performance to bad gas mileage. It is therefore important that you keep an eye on your BMW’s eccentric shaft sensor. And, if you suspect a problem, reach out to a nearby BMW service center immediately.