All modern car engines are controlled by a computer. In order for the engine to run it has about 40 sensors on it that tell the computer bits of information so it knows what to tell other bits of the engine to do e.g. fire a spark in a cylinder at just the right time.
One of these sensors is in the exhaust pipe that measures the amount of oxygen present. This is a reliable way of finding out if the correct amount of air and fuel have been injected into the cylinder to get the best fuel economy and fewest harmful emissions.
These sensors have a life of 60 000 to 80 000km. When they start to fail your car will likely start to use more petrol.
What we do
We have a piece of equipment that tests the Oxygen sensor. If it fails we would then replace it