Car Oxygen Sensor replacement & repair made easy

The sensor measures the amount of oxygen, or O2 present in the fuel / air mixture and engine emissions. Most cars have several oxygen sensors spread over the engine and its ancillaries; from the inlet manifold to the exhaust. Some cars even have a seperate sensor for each cylinder.

Usually the sensor puts out a voltage between 0.1 and 1 volt depending on the current passing through. This information from the sensors is processed by the engine's computer (ECU). The ECU in turn optimises the amount of fuel and air entering the engine to ensure optimal combustion and reduced emissions.

• The mechanic will read the ECU for possible fault codes related to the oxygen sensors.
• The mechanic will inspect the sensor and ancillaries (like the electrical connectors).
• If necessary, the mechanic will replace the sensor.
• The mechanic will advise if other components need to be replaced as well.
• The mechanic will check the sensors again.
• The mechanic will test drive the car, if necessary the mechanic will make adjustments.

Unless you are a qualified mechanic with the required skills, training and equipment to do the job, we strongly recommend a car oxygen sensor replacement is only carried out by a professional mechanic. ClickMechanic can help get you a vetted and local mechanic to carry out the work. Just enter your postcode and your car's registration number at the top of this page and select the work needed to get an instant fixed price up front.

• When the 'Check Engine' light on your dashboard is on.
• When the engine won't start or cuts out during operation.
• When the engine misfires.
• When the engine runs rough (a rough idle for example).
• When the engine doesn't perform as well as usual.
• When the car's fuel consumption is higher than usual.
• When the car fails an emissions test.

A car oxygen sensor replacement usually takes around 1 hour, but can take less or more time. Ultimately, the time that the job will take will depend on a number of factors, like your vehicle's make and model, year, as well as other factors. Select your car at the top of this page for information on job time and cost for your vehicle through ClickMechanic.

For an optimal combustion of the air / fuel mixture within the engine it is important to service the oxygen sensors as and when stipulated in the guidelines set out by your car's manufacturer. Professional and timely maintenance is essential to prevent further damage of other parts of the engine. Should you experience problems with an oxygen sensor, then it is advisable to have it inspected and, if necessary, have the sensor replaced.

Over time, an oxygen sensor can soil due to the dirty air passing along it. This decreases the sensor's ability to identify the amount of oxygen that is present in the area of the engine system it is situated. This can lead to the ECU not being able to regulate the fuel / air mixture correctly which can have as a consequence that the engine will run lean or rich. In turn the car can have poor fuel consumption, equally it might cause the car to fail an emissions test.

In many cases an oxygen sensor can be cleaned of dirt to restore its functionality. In other cases it can be that the oxygen sensor has really failed, in which case it needs to be replaced to prevent further issues and inconvenience.

If you suspect there is any issue with your oxygen sensor (also known as an O2 sensor) or there are concerns about its age or condition, book an inspection with a professional mechanic immediate effect. Driving with a faulty oxygen sensor can lead to further complications on your vehicle.

A car usually has two oxygen sensors if it has a single exhaust pipe and catalytic converter, and sensors could be independently replaced. It is advisable to check with a professional mechanic whether it is possible to just replace one sensor as this can depend on a number of factors.

The oxygen sensor or lambda sensor if often flagged during the emissions check in an MOT test. As the sensor helps regulate the fuel/air mixture going into the engine, it follows that a faulty lambda sensor is often the cause of emissions that are too high. It's recommended to check for a functioning oxygen sensor, especially prior to an MOT test.

Due to constant exposure to heat being fitted on the exhaust of the car, the oxygen sensor will eventually suffer from wear and tear over time. Contamination from debris and dust can also cause the oxygen sensor to become faulty. Typically, the oxygen or lambda sensor fails due to damage from being in close proximity to extremely high temperatures.

Oxygen sensors can typically last anywhere from 40,000 to 100,000 miles however they may need to be replaced sooner if damaged or corroded.

A faulty oxygen sensor in itself should not cause MOT failure as it is not checked as part of MOT. However, a failing sensor can lead to engine performance issues, if these result in emissions issues it is possible your vehicle can fail its MOT.