The lambda sensor, or lambda probe, works in collaboration with the catalytic converter and both are placed in the exhaust line. In new cars, there are two lambda sensors before and after the converter, and the probes "report" on the exhaust gas blown through the catalyst. The sensors measure the ratio between gasoline and air, i.e. the amount of oxygen in the exhaust. In this way, the lambda sensors ensure that the amount of gasoline is fine-tuned and that the catalytic converter can clean it.
In old petrol cars, there is only one lambda probe next to the converter. So there may be a difference in where the sensor is located, but no matter whether there is one or two, they ensure a well-functioning exhaust.
What is the difference between an oxygen sensor and a lambda sensor?
If you are wondering what an oxygen sensor is, the answer is that basically, the oxygen sensor - or the o2 sensor - is the same as a lambda sensor.
They both make sure to measure the ratio between oxygen and fuel in the exhaust gas.
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How to check if the lambda sensor is working: The engine light in your dashboard is on. That’s the lambda sensor fault symptom.
So how do you test a lambda sensor? The mechanic attaches special test equipment to see where the fault is located on the exhaust line, and if the values match.
Unfortunately you cannot check if your car's lambda sensor is defective, unless you have the right equipment. So be sure to get the mechanic's view. Your car cannot go through the MOT if the lambda sensor does not work, and you use more fuel because it does not regulate the gasoline properly.
What is the cost of a defective lambda probe?
If you experience symptoms of a broken lambda sensor, you should drive the car to a garage to have it checked. If it turns out that the lambda sensor is defect, then it must be changed - that’s what a repair includes.
A new lambda sensor costs between £100 and £200 on average (the spare part itself), and it takes a little time for the mechanic to replace it - around 1-1.5 labour hours.
That's why you often land at a price around £225 for the whole job.
Remember that you often save between 20 and 40 percent if you ask for 3 quotes on the job through Autobutler.