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What is the lambda sensor?

What is the lambda sensor?

25 October 2019, 11:47

The lambda sensor, also called an oxygen sensor, is a small probe located on the car exhaust, between the exhaust manifold and the catalytic converter. It was developed by Volvo in the 70s.

If you own a newer car, it will be equipped with 2 lambda sensors. In that case, the second sensor will be located right behind the catalytic converter.

What is it used for?

The lambda probe will adjust the fuel amount that is sent to the engine cylinders by optimizing the air and fuel mixture, which in turn will make the engine work properly. This will also impact the harmful gas emissions rate by making sure the catalytic converter is working correctly.

Therefore, the lambda sensor ensures that your car complies with the European regulations on pollution and CO2 emissions.

How does it work?

As the lambda sensor is placed before the catalytic converter, it can measure the amount of air and fuel in the unburnt hydrocarbons after the combustion.

That way, the vehicle’s Electronic Control Unit (ECU) which controls some functionalities of the engine, will receive the correct data on the emissions, and it will then release the exact quantity of gas needed. This is essential in decreasing polluting emissions.

A faulty lambda sensor?

If the lambda sensor is defective, no data will be sent to the ECU, which will then use faulty information. This will most likely increase the fuel consumption, and subsequently, the polluting emissions.

Eventually, this may lead to the clogging of the catalytic converter, which you will then have to replace.

Symptoms of a faulty lambda sensor

  • The engine warning light will show on the dashboard
  • The car jerks when starting
  • Unusually high fuel consumption
  • Low engine power during accelerating
  • A raise in emission of toxic gases

When should I replace the lambda sensor?

The lifetime of a lambda sensor is around 93,000 miles driven. However, this could be shorter depending on numerous factors that can damage it, mainly because of anomalies coming from the engine. Leaks from the exhaust can also damage the probe.

If you notice one of the signs stated above, we recommend you visit a mechanic who can test if the fault is coming from the lambda sensor. This is done with a car diagnostic tool.

In case you should soon need to take your car to MOT, be aware that a defective lambda sensor will fail your car. Do not hesitate to compare quotes on a car diagnosis from garages near you, or get quotes on the complete replacement of the lambda sensor.

Can I unplug the lambda sensor and still drive?

Driving without the lambda sensor is highly inadvisable. The spare part makes sure that your car does not emit more CO2 than allowed by the EU laws.

Moreover, even though you think that your car will be more powerful, this won’t last as the catalytic converter will have a higher risk of getting clogged.

On top of that, you will spend more money, as unplugging the lambda sensor will increase your fuel consumption by approximately 15%.

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