Attention: Lean or Rich Mixture

Based on previous post, you have learned something about the function of vehicle’s internal combustion engine. For simple recall, it works as soon as the fuel-air mixture gets into the engine’s cylinder. Actually, the process is composed of four strokes repeating constantly as soon as there’s fuel-air mixture to be utilized for the whole process. With the mixture’s important role in engine function, it is necessary to maintain appropriate ratio of the said mixture. That’s why, your vehicle is equipped with some system specifically component that aid in this aspect. The engine control unit (ECU) with the aid of oxygen sensor can detect right amount ratio of mixture.


The engine control unit (ECU) is an electronic control unit. It controls several aspect of the internal combustion engine. Simply, it detects the right amount or ratio of fuel-air mixture injected into engine’s cylinder. This unit includes several components like the oxygen sensor. The oxygen sensor is also known as lambda sensor. It is an electronic device capable of measuring appropriate ratio of mixture. Specifically, it measures the proportion of oxygen in the fluid analyzed. It was introduced in 1976 by Bosch.


Oxygen sensors are equipped in vehicles manufactured after 1980. It is also equipped to detect rich or lean mixtures. In a rich mixture, there’s lesser air than the perfect ratio. On the other hand, lean mixture has more air than the perfect ratio. The first condition may cause fuel left over after combustion. The unburned fuel will then cause pollution. The second kind of mixture tends to produce more nitrogen-oxide pollutants. This then causes poor performance and even engine damage. So, how does the oxygen sensor detect these mixtures?


The mechanism involves chemical reaction and voltage generation. The ECU looks at the voltage to determine if the mixture is lean, rich, or just right for the operation. The detection is necessary so that the ECU itself can adjust the amount of mixture entering the engine. It needs oxygen sensor to detect more accurately. This is because the amount of oxygen that the engine can pull in depends on several aspects. These aspects include altitude, air temperature, engine temperature, barometric pressure, engine loads, etc. That’s why when the sensor fails; the ECU can no longer sense the ratio of air-fuel mixture. In this case, your vehicle may perform poorly and it may also use more fuel than before. Unfortunately, your vehicle’s oxygen sensor doesn’t last forever. Several things happen as it gets old.


As your oxygen sensor gets old, its sensing capability may be reduced. At the same time, its output voltage may no longer be as high as before. This then gives inaccurate results regarding the mixture. Old and malfunctioning oxygen sensor may destroy the catalytic converter, or worse, the engine. In this case, you should check your oxygen sensor regularly. In fact, it is easy to determine if your oxygen sensor needs replacement.


When its time for you to replace your oxygen sensor, several signs may be noticed. Some vehicles are equipped with sensor reminder light. This light will alert you whenever you need to replace your oxygen sensor. If your vehicle doesn’t have sensor reminder light, better check your oxygen sensor, or have an expert to do it for you.


Aside from avoiding vehicle damage, you also need to have good working oxygen sensor condition for environmental purposes. It was explained earlier how it aids in lessening toxic emissions. With all those things aforementioned, have you now figured out the importance of your vehicle’s oxygen sensor? If yes, then you can now understand why this article is entitled as Attention: lean or rich mixture. Aside from that, you can greatly help in saving mother Earth.



One Response

  1. excellent post and pictures!

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