Sniffing exhaust all day doesn’t sound like a fun job, but as the saying goes, someone’s got to do it. Or something, rather. In this case, that something is your BMW Oxygen Sensor. Your BMW oxygen sensor has the all-important job of relaying the exhaust oxygen content back to your fuel injection computer. Why is this so important? Well, only by sampling the burned exhaust gasses does the computer know how well it has done its job upstream. It can then make corrections in the fuel/air ratio to get the correct oxygen levels in the exhaust.

The exhaust also needs to contain a certain percentage of oxygen so the catalytic converter can do its job. The oxygen sensor lets the computer know if more oxygen is necessary, since the catalytic converter actually carries on low-level combustion inside its walls. And what’s needed for combustion? Oxygen. Good job, class. Now, sitting in the exhaust gasses all day has its downside, and the BMW oxygen sensor tends to clog and fail more often than other sensors. But you can’t drive without one, so take care of any BMW oxygen sensor problems as soon as they crop up.