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What does an oxygen sensor do?

What does an oxygen sensor do?

An oxygen sensor is also known as an emission sensor. It is one of the most important sensors in a car's engine system. The main function of the oxygen sensor is to measure the residual oxygen concentration in the car's exhaust. This data is then sent to the vehicle's ECU so that the engine can adjust the fuel level accordingly, helping to maintain performance while complying with vehicle emissions regulations.

Where are oxygen sensors located?

An oxygen sensor is typically located in the threaded hole directly in front of the engine's exhaust catalyst. The exhaust catalyst is typically located near the end of the exhaust manifold, behind the muffler. Vehicles with many cylinders often have numerous sensors mounted in the branches of the exhaust system. On some models, the manufacturer installs an oxygen sensor at the rear of the exhaust system. However, the sole purpose of this sensor is to evaluate the catalytic converter's ability to treat the exhaust gas.

Where are oxygen sensors located

The Role of an Oxygen Sensor

The oxygen sensor is a component of the exhaust system that helps reduce vehicle emissions and fuel consumption. It has been required on gasoline and diesel vehicles since the 1990s. The oxygen sensor (or lambda sensor) is installed in the exhaust system before the catalytic converter, between the exhaust manifold and the catalytic converter. It informs the engine control unit of the oxygen content in the exhaust gases produced by combustion. The ECU then determines the amount of fuel to inject into the cylinders to achieve the ideal air-fuel ratio. Oxygen sensor control helps reduce fuel consumption and pollutant emissions to meet emission standards. The latest emission standards require a second oxygen sensor to be installed after the catalytic converter to determine its efficiency.

Oxygen sensor operating principle

The operating principle of an oxygen sensor is the comparison of two partial pressures of oxygen in two separate gaseous media. The zirconia that forms the sensing element has lattice defects, i.e. some of the sites that could be occupied by oxygen ions are missing. The property of this ceramic is to allow the displacement of these oxygen ions at temperatures above 600°C. The sensing element then becomes conductive. The voltage generated is a ratio between the relative difference in oxygen concentrations and the temperature of the process atmosphere.

To be able to compare these partial pressures, the oxygen probe must be supplied with a gas of known oxygen content (ambient air: %O2 = 20.9%), the so-called reference air.

By knowing the CO content, either by analysis or theoretical calculation, and using the values measured by the system oxygen probe, the user can determine the carbon potential (and oxygen concentration) of his process atmosphere.

The sensing element of oxygen probes has a limited life. Its surface layer is altered by impurities suspended in the process atmosphere. For these reasons, the user should replace the sensing element as soon as its impedance exceeds acceptable tolerances.

How to Maintain the oxygen sensor

How to Maintain the oxygen sensor?

To limit oxygen sensor wear, it is recommended that the air filter be changed regularly, the spark plugs maintained, and the engine block kept clean.

The oxygen sensor typically needs to be replaced every 100,000 miles or so, but there are some obvious signs that can alert you to its condition:

  • The engine symbol on the dashboard while driving
  • Engine bucking
  • Lack of power when accelerating
  • Smoke from the exhaust

In all cases, remember to follow the vehicle's maintenance schedule by referring to the owner's manual provided by the manufacturer, as each vehicle has different recommendations.

How do I check the oxygen sensor?

The easiest way to check the integrity of a oxygen sensor is to have a professional connect the vehicle to the manufacturer's diagnostic tool.

A quick visual inspection can also help assess its condition:

  • An improperly installed oxygen sensor may be deformed.
  • Its wires may be melted by the heat from the exhaust.
  • Scale can form on the sensor, preventing it from working.
  • Rust may form on its contacts.
  • Deposits may form from oil or fuel additives burned in the engine.

How do I replace the oxygen sensor?

Replacing the oxygen sensor requires some knowledge and equipment.

  • First, if your vehicle has two oxygen sensors, determine which one is defective.
  • Disconnect the battery and place the vehicle on jack stands.
  • Disconnect the plug that connects the engine wiring harness to the oxygen sensor before removing the sensor.
  • Compare the new oxygen sensor to the one just removed.
  • Install the new sensor before reconnecting it to its connector.
  • Reconnect the battery and start the engine to verify installation.

Why do I need to clean the oxygen sensor

Why do I need to clean the oxygen sensor?

In order to drive with the best performance, the function of the sensor components on the car must be exploited to the fullest. In particular, the oxygen sensor is an electronic device located in the exhaust pipes, in direct contact with the emissions from the engine's combustion chamber. Consequently, this sensor will perform the task of measuring the quality of the emission. It then sends a signal to the ECU to evaluate and adjust the fuel ratio and the amount of air entering the combustion chamber to the most appropriate level.

With this role, the oxygen sensor in the car directly affects vehicle performance, avoiding errors such as unstable speed, slow acceleration and fuel consumption,... In addition, it also guarantees standard emissions and does not pollute the environment. Drivers should therefore check the oxygen sensor, recommended 1-2 times a year. This will ensure quick detection of any problems, as well as cleaning, repair or replacement of the oxygen sensor to ensure stable performance.

Note: Keep in mind that oxygen sensors don't get dirty unless you have serious problems such as a bad fuel injector, bad spark plugs, or cracked ignition coils.

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