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IMPORTANCE OF OXYGEN SENSOR TO PRESERVE THE AIR QUALITY Laws in many countries are becoming increasingly rigorous on automotive emissions. The three-way catalytic converter is the most common method used today to make exhaust gas less toxic. But the catalytic converter only works efficiently when the air-fuel mixture is maintained within strict limits. This is where the oxygen sensor is so important. NGK/NTK, the largest worldwide manufacturer of this product, makes more than 10 million items per year. The oxygen sensor detects the amount of oxygen in the exhaust gas, varying the exit signal to the lambda sensor. The lambda sensor in turn tells the engine's Electronic Control Unit (ECU) to change the proportion of air and fuel, also changing the combustion timing. This cycle, known as closed loop, ensures that the air-fuel mixture is always adequate to provide the efficient catalytic conversion. It also guarantees good performance. Lambda is a letter of the Greek alphabet that is commonly used in engineering to represent the relation between air and fuel. A lambda of 1 represents the ideal mixture (about 13:1 for gasoline with 24% alcohol); less than 1 is a rich mixture; more than 1 is a lean mixture. The cone-shaped sensor is made of a ceramic material (zirconium dioxide) that is sensitive to oxygen, and it's encased in platinum. NGK/NTK makes various types of lambda sensors for gasoline and alcohol powered engines. Already 14 models are available on the replacement parts market for Fiat vehicles (Uno, Elba, Fiorino, Tempra, Tipo, Palio, Weekend, Siena); Ford (Escort, Verona, Versailles, Royale, Fiesta, and Ka); GM (Omega, Vectra, and Astra); Renault (19 and Clio); VW (Gol, Parati, Saveiro, Santana, Quantum, Apolo, Logus, Pointer, and Polo). Some auto makers recommend changing the lambda sensor every 40,000 km. Certain factors may affect their useful life, however: lack of periodic maintenance, driving conditions, other engine conditions, and use of inadequate additives in the fuel.
NGK/NTK notes that a faulty sensor will cause a vehicle to fail
emission tests, suffer performance problems, high fuel consumption,
and overheating in the catalytic converter, which may cause damage.
The most inexpensive precaution is changing the sensor to avoid
any greater losses . |
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