1996 Sephia - I have P0135 code set. Inspection due this month, Texas.
I have checked the continuity of the heater by unplugging the sensor connector and checking with VOM. It is good. I guess I will have to start looking at wire harness.
I fear that if I have work done by shop they will replace the sensor and cost me money, not solving the problem. And tracing wire problem is a money hungry witch hunt at a shop.
By the way, the 2nd sensor, in the center of the exhaust pipe under the car, has different gender connector on harness than the first sensor under discussion. I reseated both connectors to see if that would solve the problem. Didn't.
By the way, airchecktexas, the state agency in control of testing, has a bulletin that the non-continuous monitors in the 96 Sephia will often not go to yes (complete) and the inspection can be done by exhaust measuring in this case. I have got my monitors to go to yes by driving three round trips of over 50 miles each.
I am using the obd tool from http://www.obd-2.com/