The oxygen sensor is installed in the exhaust manifold or pipe, making it difficult to loosen when the engine is cold. To avoid damaging the sensor or its mounting threads, start and run the engine for a minute or two before attempting to remove it. There are a series of steps you should take to do this. Find the oxygen sensor in the exhaust manifold for 1994 models and 1995 B6 SOHC models, then disconnect the electrical connector before unscrewing it with an oxygen sensor socket if available. In addition, for 1995 BP DOHC models and all 1996 and later four-cylinder models unplug the upstream oxygen sensor electrical connector and remove it using an oxygen sensor socket. Reuse of this old device requires application of anti-seize compound on its threads as well as these other ones too. Remove the coolant reservoir or upper intake manifold depending on the location of upstream O2 sensors in Sportage V6 models. This will go ahead up until disengagement from electric connectors and unscrewing by use of an oxygen sensor wrench respectively in relation to every particular downstream one that needs reusing previously used anti-seize compound on their threads. Raise front of vehicle; detach engine under cover/splash shield; unplug electrical connector; and unscrew using an O2S wrench in reference to each respective downstream one which will be reused old as well (apply anti-seize compound to threads).
