Diagnostics An oxygen sensor that’s going bad or has failed altogether won’t always throw a check engine light or trip a diagnostic trouble code. Sometimes if there’s an internal problem ...

Finally, a bad O2 sensor can have other consequences also. Besides potentially causing damage to your vehicle, you'll also probably fail an emissions test if you have a faulty O2 sensor.

One of the most common reasons your check engine light comes on is a faulty oxygen sensor. Here's how to detect problems with the sensors and how to fix them.

Oxygen sensors are not among the maintenance items that need to be replaced regularly, so they typically are replaced only when they fail.

Your vehicle's crankshaft sensor can be, well, cranky. But it's also a key part you can't do without. So what makes one fail? And how do you know if it's bad?