When fuels are combusted, a number of harmless compounds such as water, carbon dioxide and nitrogen are produced, as well as a number of dangerous pollutants - such as carbon monoxide, nitrogen oxides and hydrocarbons.
For many years now, a battle has been waged against these harmful emissions by politics and industry. For example, at the end of the 1980s every new vehicle with a petrol engine had a regulated catalytic convertor which reduced harmful emissions.
The catalytic converter's ability to fulfil this task is partly ensured by the lambda sensor. That is because it guarantees the catalytic converter optimal operating conditions.