2002 Explorer XLT w/ 36K. My check engine light came on on sunday, in which I hooked it up to my OBDII reader. A PO136 is the code that came up. O2 Sensor Bank 1 Sensor 2. I cleared the code and was planning on getting the part next week. The CEL remained off for a few days and then came back on, which is normal, however starting up the car today the CEL is now off, and I have not replaced any parts. My question is: Is my O2 sensor fine and Do I just have an exhaust leak, or bad O2 electrical connection. Or should I replace my O2 sensor if the light comes back again. if so which o2 sensor is bank 1 sensor 2?

Bank 1 I believe is the drivers side. Sensor 2 would be the 2nd O2 sensor on the exhaust starting at the engine. I believe it's on the pipe before the catalytic converter. I have a 98 so it may be different. If the light is out it's probably functional. I've read where you can clean them but haven't had the situation arise yet. I changed 1 before I heard you can clean them. But cleaning depends on why it faulted. Bets I can do...Hope it helps.