Fits：For 1998 Chevy Tracker Downstream O2 Oxygen SensorFor 1999-2000 Chevy Tracker Non-Calif-ESV Downstream O2 Oxygen SensorFor 1996-1997 Geo Tracker Downstream O2 Oxygen SensorSpecifications: Brand New Bodeman Oxygen Sensor Downstream Sensor 4 wire configurationNote: For clarification purposes:Upstream location is between the catalytic converter and the engineDownstream location is between the catalytic converter and the tailpipe Suggestion of Replacement:Normally, technicians advise the owners to replace their oxygen sensor after using two years or vehicles run more than 6W kilometers. By using new oxygen sensor,it may save about 15% engine for your vehicles. If you have a bad O2 sensor causing your vehicle to fail an emission test then this is the part for you.