Which oxygen sensor is considered sensor 2 and how do you fix it?

Answer 1

In most applications the the #2 O2 sensor is the one downstream. Imagine your exhaust is a river flowing and the downstream thing makes more sense. Most inline engines only have two o2s, and the one behind the catalytic converter is #2. In V configurations there is the added distinction of bank 1 and bank 2. This refers to each side of the motor and varies with each manufacturer as to which one is which. As for fixing it, assuming the problem is a worn out sensor and not a wiring problem, replace it. They are solid-state non-serviceable parts and there ain't nothing you can do to get it working again. Bear in mind that all the sensors in the exhaust system have experienced the exact same conditions and should be replaced when one fails - ideally. Practicality and $ often dictate that only the dead one gets replaced. Depending one the programming in your vehicle, you may need to reset the adaptive fuel trim after replacing the O2, call your friendly neighborhood dealer for specifics on your particular vehicle. A little heat will help unstick any siezed sensors, get the boss in the pipe where it screws in red hot and it'll come out like butter. Watch for fuel leaks und the car BEFORE lighting the torch or the dead sensor may no longer be the cars biggest issue.