my 1996 civic dx failed a state emissions test. they gave me the followong fault code: PO135 02 sensor heater circuit malfunction (Bank 1 Sensor 1) I'm trying to figure out which sensor is bad. top or bottom?

 

sensor 1 is the primary oxygen sensor......that is the one up top

 

Thats the top, on the exhaust manifold, I'm having the same trouble. Let me know if your light goes out after the replacement.