Toyota Repair: Poor Fuel Consumption, 1997 lexus lx450, lexus lx450

Question
I have a 1997 Lexus LX450 which previously had poor acceleration.  I traced the problem to corroded terminals on the vehicle wiring harness for the pre-Cat O2 sensor.  I replaced the terminals and the vehicle seems to run fine (acceleration and perf is normal), but now my fuel economy has dropped to 18-20L/ 100 km (Previosuly it was 13-15L/100 km). I had the problem for approx 1.5 months and accumulated approximately 1500 km before I fixed the terminals on the O2 wire harness. Could my O2 sensor now be damaged?

Answer
That is possible, the sesnors should be tested for correct operation by connecting a diagnostic scantool and then observing the voltage waveforms of the sensors, a good technician can interpret these signals to see whether the sensors are working efficiently or not.