The air-fuel mixture in an engine’s combustion chamber can affect how hot, how quickly and how cleanly the fuel burns. For optimum combustion, the air-to-fuel ratio needs to be within a certain window. For specific driving conditions, the engine may run in sub-optimal conditions. For example, to be more fuel efficient, the engine may run on a ‘lean’ mixture. In contrast, to deliver high power performance, the A/F mixture needs to be ‘rich’. Such specific mixtures cannot be maintained for a long period of time without risking excessive emissions or even causing damage to the engine or the catalytic converter.
Lambda sensors work constantly to keep the air-fuel ratio correct by monitoring the quantity of unburned oxygen in the exhaust gases and feeding this information back to the electronic control unit (ECU), which can then dynamically adjust the air-fuel mixture to keep it close to the ‘stoichiometric point’ – the ideal ratio at which the catalytic converter will function optimally and keep emissions to a minimum.
Lambda sensors can in fact fulfil two roles: regulating sensors, placed before the catalytic converter, and diagnostic sensors, fitted after the catalyst as an extra layer of security to ensure the converter is doing its job.
DENSO’s range of proven OE-quality lambda sensors is optimised for the widest possible car parc coverage with fewer part numbers, making part sourcing easy for distributors and workshops.