Oxygen Sensor – O2 Sensor

The Oxygen Sensor – O2 Sensor (Oxygen Sensor) is an automotive technology that began to be implemented in vehicles in 1980. And it becomes part of the components of the emission control system. Find out below its operation and importance in your vehicle. As well as its physical characteristics and possible failures.

What is the Oxygen Sensor?

It is an electronic component of the census. It also receives the name of a lambda probe. It is a rigid element since its shape is that of a small and short cylinder made with an element called Zirconium and coated in ceramic to withstand the temperature.

Some oxygen sensors have a small metal housing for protection, and this has several lines of perforations for combustion gases to enter through them.

Where the Oxygen Sensor located in your vehicle?

To know its location, look at the exhaust pipe, specifically at the engine outlet; after the exhaust manifold, you will see it. There are vehicles of modern automotive technology, to which manufacturers have integrated two oxygen sensor units. They put one at the outlet of the exhaust manifold and another after where the catalyst goes. Thus they can measure the total efficiency of the emissions system.

Oxygen Sensor Function

The sensor has the basic function of informing the ECU of the amount of oxygen in the gases that the running engine expels. Its purpose establishes that efficient consumption can be achieved and the least amount of harmful gases released into the environment.

How does the O2 Sensor work?

To understand how the O2 Sensor works, first, you must understand how the combustion process occurs. For the fuel to be burned inside the engine, a spark must be generated by coil voltage, which originates from the spark plugs. Air enters the chamber of each cylinder through the intake valve, and if there is air, there is oxygen present.

The atmosphere is already there for the controlled explosion, fuel injection, air – oxygen, and spark. When this mixture is activated, combustion is generated, creating the gases that are displaced by the exhaust valves. They pass the outlet manifold and are detected by the Oxygen Sensor on their way through the exhaust pipe.

Gases cause a chemical reaction when in contact with the O2 Sensor. This reaction generates a voltage that travels to the central ECU of the vehicle and indicates the quality of the fuel mixture. From there, it will take care of maintaining or correcting parameters such as fuel injection and air intake.

Interference of the Oxygen Sensor on other systems

The O2 Sensor has a direct influence on the fuel injection system and how to regulate the air intake to the engine. Of course, it does this by sending the respective electrical signals to the ECU.

Depending on the amount of oxygen in the exhaust gas, the ECU will adjust the fuel injection timing. This process is continuous, thanks to the Oxygen Sensor.

Types of Oxygen Sensor

Although they are all very similar in physical appearance, at least some differences can be found in the oxygen sensors. Perhaps the most notable is because of the wiring or connection pins.

Some O2 sensors have 2, 3, or even 4 pins, which in turn will be seen in the output branch diagram.

Classification of oxygen sensors

The process itself gives the classification of these sensors to initiate its function.

  • Unheated: Older, first-generation oxygen sensors have an estimated time of several minutes. This is because they have no heating or ignition voltage signal. So you have to wait for the same exhaust gases to heat it up.
  • With heating: These have 3 or 4 cables and through one of them the sensor receives an electrical excitation that allows it to be activated a few seconds after the engine starts.

OBD2 Protocol Codes Related to the O2 Sensor

When scanning the sensor, the following codes may appear, which have the following meanings:

  • P0133 : Slow or late response.
  • P0134 : Static signal.
  • P0171 : Lean mixture.
  • P0172 : Rich mix.

Oxygen Sensor Faults

The most recurrent fault is directly associated with the fuel mixture. For example, if the mixture has little air, that is little presence of oxygen. There will then be an excess of unburned fuel on ignition. This condition is known as a rich mix. And it is very harmful because there will be more gases that pollute.

If it is the opposite, less fuel injection and more air, the mixture is lean. It is affecting engine performance.

Other O2 Sensor Failure

There are other common faults due to the position where the Oxygen Sensor is located and associated with high temperature, for example:

  • Sulfated connection.
  • Overheated wiring.
  • Crystallized and brittle harness.

Symptoms of a damaged Oxygen Sensor failure

The symptoms are defined, although they can also be associated with other sensors. If this sensor fails, you will notice the following:

  • Increase fuel consumption.
  • Greater emission of exhaust gases.
  • Problems with power, when starting.

Method to test the Oxygen Sensor

The method is quite essential to check the operation of the O2 Sensor of a cable; it is referred to as bank 1, or bank one sensor 2, with the dual sensor.

  • Using a DC multimeter, place the tip of the meter on the positive sensor lead. And with the other end, make contact with the negative of the battery. The grounding phase is created by the sensor itself due to its metal housing.
  • The Oxygen Sensor should flash several times in less than one second.
  • If you measure the voltage, it should be the closest to 0.9 volt. As maximum value. And the minimum should be almost 0.1.
  • If the sensor has 2 or 3 wires, the procedure is similar, only with the other clamp of the multimeter you will ground another of the wires that is ground.
  • Finally, there is the 4-wire one. This Oxygen Sensor has a signal cable and a constant ground cable, which comes from the ECU. Therefore the values will be more defined.

So, knowing if it is wrong can be a relatively easy task.

How to maintain the Oxygen Sensor?

Cleaning the sensor is very easy, and you can do it yourself. Have some thinner or carb cleaner on hand.

  • Wait for the engine and exhaust to cool down. Disconnect the harness carefully.
  • Remove the sensor and apply the solvent to it so that it drains it off. And get the dirt out.
  • Wait for it to dry at room temperature and reinstall.

Finally, we can indicate that the manufacturers give the Oxygen Sensor a maintenance or replacement time of at least 40,000 and 50,000 kilometers. Therefore, the more informed you are of the maintenance and operation of this O2 Sensor in your vehicle, the better performance you will achieve.

Oxygen Sensor – O2 Sensor

Hi, this is Viney Bhatia, a blogger, an engineer, and your virtual mechanic. You'll get all the latest information about cars, reviews, tips, service methods, and various other things related to automobiles on our blog.

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