P0140 99 Bonneville?

Question

Replaced rear O2 sensor because it was time, 150K. Installed new one and Got MIL P0140. Turned MIL off and Replaced w/ GM O2 sensor from dealer, still MIL P0140 came back on within 10 miles. Wires look good, I just changed the sensor, like i have done 100 times with no issues. Can not find a bad fuse, all look good. No driveability issues before or after the change. Any suggestions?

Answer 1

here are the diagnostic procedures 

with wiring and steps