Originally Posted by Kingtal0n

check your signal wire at the ECU by following a pinout, and check(compare) for continuity at the signal wire of the sensor on the harness end. You can also check for voltage and ground, it should have neither. The narrowband sensor creates its own voltage signal (which is why you see 1-wire O2 sensors)

PVC = poly vinyl chloride
PCV = positive crankcase ventillation

An exhaust leak would show a lean condition. I only mentioned it because if the leak is near the wideband, the wideband will show lean. (meaning that the leak is far away from the narrowband)

furthermore, if you want to cheaply change the o2 sensor, buy the cheapest 1-wire you can find from a local auto parts store. You can literally ask them if you can look in each box and price check the 1-wire sensors until you find one that is about $8 or so. then wire that 1-wire to the signal wire going to your
ECU. Once the car warms up, it will start working.