lambda sensor replacement

What does a lambda sensor do?

Lambda sensors measure the amount of oxygen in the exhaust fumes emitted from your vehicle, to ensure your engine is burning fuel correctly. Fitted in both petrol and diesel vehicles, they help to reduce the number of harmful emissions, primarily gases such as carbon monoxide, and pollutants, produced by your car.

The sensors are designed to work within government exhaust gas legislation. Due to the role they play in the operation of your car, they are also widely known as oxygen sensors or O2 sensors.

Your lambda sensor converts the amount of oxygen present in your exhaust into an electric signal and sends the signal to the computer that controls your engine operation. The ECU (engine control unit) processes the readings and sends the information back to the engine. The engine then makes compensations of how to mix fuel and air to get the ratio back to where it needs to be.

How often should a lambda sensor need replacing?

Several things can affect your sensor's lifespan, but typically you should replace your lambda sensor every 50k-100k miles. Your sensor should be checked periodically, to ensure its correct operation.

Due to the nature of their operation and their position in an extremely hot and dirty environment, the lambda sensor will wear out over time. In addition, vibrations or damage to connectors and/or wires can also cause failure. Another common cause of premature failure is contamination, which will most likely require a replacement sensor to be fitted.

The law, vehicle regulations and your MOT

A faulty lambda sensor is often flagged up during an MOT test. The current MOT test includes an emissions check, so any unusual emission results will be reported, and an advisory will be given on what work needs to be done.

Remember, it is advisable to check the sensor regularly, to ensure it functions well. It could save your car from failing an MOT, and improve your car’s fuel consumption, saving you money down the line.

What causes a lambda sensor to break?

Due to the nature of their operation and their position in an extremely hot and dirty environment, your lambda sensor will wear out over time. Damage to the heater element of the sensor is the most frequent fault associated with lambda sensors. In addition, vibrations or damage to connectors and/or wires can also cause failure. Another common cause of premature failure is contamination from debris, dust and carbon.

When should a lambda sensor be replaced?

Several things can affect your sensor's lifespan, but typically, it should last anywhere between 50k and 100k miles.

In the past sensors didn’t have a heating element, so required the exhaust temperature to reach a specific heat to operate. Nowadays modern sensors are fitted with a heating element, taking a lot of the pressure off the sensor. These newer sensors have a much longer lifespan.

Your sensor should be checked periodically, to ensure its correct operation.

What are the signs of a bad lambda sensor?

Usually, there a few signs you can look for:

• Your engine performance will suffer—often misfiring, cutting out or not starting at all

• When your engine is idling, or just ticking over, it will feel rough and lumpy compared to normal

• Fuel consumption is higher than normal

• Your car has failed an emission test

• The engine warning light will illuminate on your dashboard

What happens during a lambda sensor replacement?

During the repair our certified mechanics will:

• Read the ECU for possible fault codes related to the lambda sensor.

• They will inspect the sensor and ancillaries (like the electrical connectors).

• If necessary, the mechanic will replace the lambda sensor.

• The mechanic will advise if other components need to be replaced as well.

• They will check the sensors again.

• The mechanic will test drive the car, and make any final adjustments.

What is the average life of a lambda sensor?

Several things can affect the lifespan of your lambda sensor, but typically, it should last anywhere between 50k and 100k miles. The sensor may have to be replaced sooner if it becomes damaged or corroded.

Can you drive with a broken lambda sensor?

Technically you can drive with a faulty lambda sensor, however we don’t recommend it. You'll want to change it as soon as possible, because otherwise, you'll be spending more money on fuel and you risk having to splash out on a new catalytic converter as well.

What happens if you don't change the lambda sensor?

A broken or faulty lambda sensor will lead to the ECU not being able to regulate the fuel / air mixture correctly which can result in the engine running lean or rich. In turn the car will likely have poor fuel consumption, it might also cause the car to fail an emissions test.