Precaution is required when connecting an oxygen sensor because it is fitted in the exhaust manifold or exhaust pipe, which shrinks when cold and becomes tight when tightening when the engine is cold. Care has to be taken not to burn oneself and it is advisable to start the engine and let it run for one or two minutes for the sensor to warm up, at the same time taking care not to force thread or damage the sensor. When installing or replacing oxygen sensor, care should be taken to notice that the sensor has a pigtail and an electrical connector that is supposed to be left intact as removing or damaging this part will make the sensor to be as good as useless. Do not allow any of the grease, dirt or other contaminants get to the electrical connector and the louvered end of the sensor, and never apply any cleaning solvents on it. Oxygen sensors are very sensitive and should not be thrown or touched as they may break. Particularly, be sure the silicone boot on the sensor is at the correct place to avoid melting and enable performance in its supposed manner. The vehicle may not work as it is supposed to for several days after the sensor has been replaced, and this is because the sensor has to go through what is commonly referred to as the 'learn process', and this may require the use of the GM's TECH-2 scan tool to hasten this process. The upstream oxygen sensor in the CVTiest 1.4L models is situated on the top of the
Catalytic Converter, to the immediate right of the turbocharger while that of the CVTiest 1.8L models is fashioned onto mid-section of the exhaust manifold. To begin with, switch off the ignition key and then unbolt the exhaust manifold heat shield for the 1.8L models and the upstream oxygen sensor electrical connection for the 1.4L models near the throttle body hose, for the 1.8L models it can be done near the thermostat housing. Prise with an oxygen sensor socket the upstream oxygen sensor, using penetrant if the bolt is tightly canted. For the downstream oxygen sensor, the ignition key should be OFF / and the vehicle raised on jackstands securely / the electrical connector is to be found at the back side of the engine on a bracket and one must disconnect it. Disconnect the downstream oxygen sensor, if it requires you to use penetrant, then go ahead and apply it. Reinstall the old sensor and if so, apply anti seize compound to the threads to ease the removal in future, other if a new sensor is used the threads are already oiled with anti seize compound. It is vice versa of removal where ensure the sensor is well tightened up to the specified torque of the area.