Have you given any thought lately to your BMW 540i oxygen sensor? Many car owners do not even realize they have a 540i oxygen sensor—but it is there, sitting near your exhaust manifold and performing an important job. Your BMW 540i oxygen sensor is responsible for monitoring the oxygen content of your exhaust as it leaves your combustion cylinders. This is an important function, because your engine relies on a precise mixture of fuel and oxygen to run properly.

The 540i oxygen sensor must check your hot exhaust hundreds of times each minute and send the information it gathers to your car's computer without fail. As you can imagine, the BMW 540i oxygen sensor works under some difficult conditions, and is subject to some damage over time.

Unfortunately, it can be hard to diagnose a faulty 540i oxygen sensor. It is still important that you keep track of your BMW 540i oxygen sensor and make sure it is working, because a bad 540i oxygen sensor means wasted fuel, poor engine performance, and excess heat that can damage other engine parts. The extra fuel your car injects to compensate when it can't receive information from a faulty BMW 540i oxygen sensor is not only wasted money, it can also cause a more expensive problem when it damages your catalytic converter. A damaged 540i oxygen sensor may be detected during an emissions test, or you may be able to trace a drop in gas mileage to a faulty BMW 540i oxygen sensor.If your exhaust emits black smoke or a rotten egg odor, it is a good idea to replace your 540i oxygen sensor, as that may correct the problem.