Why Do NOx Sensors Fail?

Given their location, it will come as no surprise that soot buildup on the sensor is one of the most common reasons for failure.

It’s also not unheard of that damaged cables can be the root cause of the issue, and in this case, it should be visually apparent where the problem lies.

Sometimes it’s not the actual NOx sensor itself that fails, but rather the internal probe used to determine the NOx levels has generated a fault.

Given that it’s a general wear-and-tear item that you should need to expect to replace eventually, there are many potential reasons for NOx sensor failure.