[dennyo]

tony, i tried cleaning all the contacts with crc cleaner and still no luck.I now have 2 bosch and one ngk installed all new within the last couple years. I'm starting to suspect it's not the sensors.Perhaps exhaust related. One thing I noticed, in the FSM a code po145 is for front sensor left side and po139 is for rear sensor slow response.My actron scanner says that po145 is for rear sensor slow response.Just the opposite.Thats why I changed them all.One thing(at least on my 96) the harness plug by the back of the block is different for the front and rear sensors even though the same sensor is used.I can't swap them over except at the rear cat.I haven't had any problems with any of the other sensors so I don't think it's the brand of sensor.