The oxygen sensor in your Volkswagen Passat measures the air and fuel being burned in the engine. It then sends this information to the Passat's ECU so that the air-fuel mix can be adjusted accordingly. Over time, the oxygen sensor will fail. After 100,000 miles, you should check the O2 sensor in your Passat and replace it if and when the engine light comes on. The ECU will produce a code that can be checked for free at most auto-parts stores by the employees that work there. When the code for the O2 sensor comes up, you'll need to know how to change a Passat oxygen sensor.
Turn the Passat's engine off if it is running. If you recently drove the vehicle, let the engine cool down. The O2 sensor and the exhaust system will be very hot, and you'll need to wait for them to be completely cool to the touch in order to work on them.
Jack up the Passat using the front jack points on the vehicle. The front jack points are located behind the radiator.
Place a jack stand under each of the front pinch welds and lower the Passat onto the jack stands.
Climb underneath the Passat and locate the O2 sensors. There should be one before and one after the catalytic converter.
Unplug the electrical connector going to the O2 housing.
Remove the O2 sensor using the O2 sensor removal tool.
Place a small amount of anti-seize compound on the threads of the new oxygen sensor and install the new O2 sensor.
Plug the electrical connector back into the O2 sensor.
Lower the Passat to the ground.
