Before attributing the oxygen sensor to driveability problems, thorough tests should be carried out. The PCM controls the engine air/fuel ratio through the upstream O2S. The downstream O2S is used in the catalyst monitor system. A working O2S needs good connections, air supply, temperature, and unleaded fuel. HO2S faults are detected by the EEC system through trouble codes. This is done by checking O2S signal voltage with a voltmeter which should range from 100 to 900 millivolts for both sensors. Be careful during sensor removal so as not to damage it, get it dirty, or use cleaning solvents. Install an anti-seize compound on the threads before screwing in the sensor. Lifting the vehicle up is part of the removal process, then comes detaching the electrical connector, unscrewing the old sensor using a specialized socket, applying anti-seize compound, tightening a new sensor safely and finally connecting the electrical connector.