Why Does the Crankshaft Position Sensor Malfunction in a BMW?

The crankshaft position sensor is a small component of your BMW’s engine management system. It checks the position and rotation rate of the crankshaft and passes this information to the engine control unit (ECU). Based on this information the ECU controls such important aspects as fuel injection and ignition timing.

When the crankshaft position sensor goes out of service then your BMW may experience troubles with the start-up process and may run roughly, accelerate badly or stop altogether. As the sensor performs an important function, the symptoms should be addressed promptly.

What Does the Crankshaft Position Sensor Do?

The crankshaft position sensor gives the engine control unit precise information regarding the position of the crankshaft while the engine operates. With this information, the ECU establishes the proper moment of fuel injection and ignition.

An operating sensor ensures the engine runs smoothly. When the sensor's signal is weak, incorrect or intermittent then the ECU cannot get precise information about the position of the crankshaft.

Common Causes of Failure of the Crankshaft Position Sensor

Natural Wear and Tear

Just like any other part of the engine, the crankshaft position sensor wears out through use. Heat from the engine, vibration and temperature changes may affect its internal parts.

Over time, the sensor may not send accurate signals and fail. Older models of BMW cars may have issues with this type of sensor especially if it has never been changed.

Damaged or Defective Wiring

In some cases the sensor might not be the primary cause of the trouble. Inappropriate electrical connection or damaged wiring hinders the signal from reaching the ECU.

The wiring harness can be affected by the vibration of the engine, exposure to heat, contamination by oil or physical damage. An inappropriate connection may block the electrical signal.

Some common problems with the wiring harness are:

• Damaged wiring

• Loose electrical connections

• Corrosion of the terminals

• Defective insulation

• Defective contact in the connector

Contamination by Oil or Dust

Oil leaks or dirt contamination may affect the functioning of the sensor. Depending on the BMW engine type, the sensor could be contaminated by contaminants present in the engine.

Oil contamination can affect the wiring as well. In case of an engine oil leak in proximity to the sensor, fixing the leak would be part of the procedure along with fixing the sensor.

Symptoms of a Malfunctioning Crankshaft Position Sensor

There are certain symptoms that a malfunctioning crankshaft position sensor causes. They may differ based on the model of the car, engine and the level of malfunction.

Here are some of them:

• Trouble starting the engine

• Cranking the engine without starting

• Unusual stalling of the engine

• Difficult engine idling

• Poor acceleration

• Decreased engine power

• Intermittent starting problems

• Bad fuel consumption

• Check engine light illumination

How Is the Problem Diagnosed?

The diagnosis of a crankshaft position sensor problem does not only involve replacement of the sensor. The first thing a mechanic may do when trying to diagnose such a problem is to scan the vehicle's computer system.

The following steps that may be done to diagnose a problem with the sensor include:

• Scanning for diagnostic trouble codes

• Inspecting the sensor and its connector

• Checking the wiring for any damage

• Testing the voltage and resistance

• Checking the sensor signal

• Checking crankshaft-related parts

• Checking for any dirt or oil near the sensor

What Will Happen If You Ignore the Problem?

It is never a good idea to ignore the problems associated with a crankshaft position sensor problem. A malfunction of the sensor can lead to problems such as unexpected car stalling and even an inability to start the engine. Moreover, a stalled car during a drive may lead to dangerous situations especially in heavy traffic.

How Do You Avoid Sensor Problems?

There is no proper method to ensure that you will never encounter any kind of crankshaft position sensor failure because sensors may eventually wear down. But you can maintain your BMW properly to decrease the likelihood of problems.

Make sure you are following your BMW’s recommended maintenance and make sure that you are monitoring oil leaks, warning lights, engine performance problems and starting problems.

You should also do the following:

• Fix any oil leak problems right away

• Do not ignore warning lights

• Fix any electrical problems soon

• Stick to your maintenance schedule

• Deal with any starting or stalling problems immediately

Conclusion

If you are having problems with your BMW such as difficulty starting, engine stalling, rough operation, poor acceleration or the check engine light then it may be a good idea to have your crankshaft position sensor examined.

In order to provide professional BMW service and repair, we can diagnose the problem and suggest the appropriate fix for your car. Come visit our shop now and have your BMW diagnosed by our technicians.

Santa Barbara Autowerks is a renowned car repair shop name in Santa Barbara. We are committed to offering the highest level of services to our beloved customers so that they can grab the fun of their vehicles completely.