Replacement Need Physical Demonstration....! Your Mechanic Or If You Can Access It..Can Simply Open It...(Via Spanner Or There Comes A Separate Socket To Open O2 Sensor With Rachet..Its Cutted From Side) ...Tighten New...And Install Grip Back...Simple
However I Always Recommend A NEW 02 Sensor But As They Are Considered Rare Creatures Here Around So You Can Try Your Luck On Kabli And Test Them To Verify If They Are Good/Bad....Reason Of This Thread Is Same To Test It As Everyone Knows NEW Will Def Work...!
Issues If Not Replaced Will Be Heavy On Fuel Consumption/ Check Engine Light / Carbon Fouled Plugs And CEL Popping Up