What is the purpose of the O2 / Lambda sensor?

The O2 (Oxygen) Sensor or Lambda Sensor as it is known in the the trade is located before the Catalytic Converter in the exhaust system.
o2_lambda_sensor_smallThe job of this probe is to measure the amount of oxygen left in the remaining burnt gases as they exit the engine and send this information to the ECU (Engine Management Unit). The ECU can then calculate the correct fuel / air mixture for the ideal combustion which lowers fuel consumption and in turn reduces emissions. This is important for passing MOT and roadside emissions tests.
More recent regulations require a second 02 sensor to be positioned after the Catalytic Converter so that the effectiveness of the converter can be measured.

Why you should the Lambda / 02 Sensor be replaced?

If there the sensor is faulty it will send incorrect readings to the ECU and therefore the calculated air to fuel ratios will be incorrect. This will cause the engine to stutter, run lumpy and increase fuel consumption.
engine_management_light.jpg (from Decarbonise DPF page)



When should the Lambda / 02 Sensor be replaced?

As long as it’s not shortened by other engine malfunctions the average lifespan of an 02 sensor is 80,000 to 90,0000 miles.
Exhaust leaks can damage the sensor probe which can lead to dangerously high temperatures. The probe canse also become contaminated by unburned fuel, if this occurs it is irreversible.
Following a strict servicing routine, including the usual oil changes, spark plugs, air filters etc, is required to ensure maximum life of the sensor.

Signs that your Lambda / O2 Sensor needs to be replaced:

  • The engine starts to stutter or suddenly suffers from reduced performance
  • The check engine management light illuminates

The easiest way to diagnosis a faulty Lambda / 02 sensor is with an OBD (On-Board Diagnostic computer). Unless you have access to an OBD reader and are competent in using one this should be completed by a professional.

Typically garages charge up to £70 for such a diagnostic, alternatively we include a FREE diagnostic with all of our Carbon Cleaning Services starting from just £89.99


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Call us for multi-vehicle discounting (as much as £50 per vehicle!)

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If the Lambda Sensor / O2 Sensor is…



Saturated dark brown then it’s likely there has been an unbalanced air to fuel mixture over a considerable period of miles.



Saturated with a grainy stain then it’s likely there’s been an anti-freeze leak into the engine.




Saturated white or red then it’ll have been caused by a fuel additive.




Saturated black and oily will tend to be caused by excessive oil consumption.

Cleaning your Lambda Sensor / O2 Sensor?

There are numerous ways to clean or replace the Lambda Sensor / 02 Sensor with varying prices.

The costliest option is a complete replacement part. Most mechanics will recommend this – Why? It’s generally their only solution. The price of a Lambda / O2 sensor varies on average between £180 and £300. NOTE: Newer vehicles have two sensors and it’s not uncommon that if one has been damaged the other will have been as well

CarbonCleaning Lambda Sensor / O2 Sensor cleaning

image010If your vehicle requires professional intervention to clean the Lambda / O2 Sensor there is no better alternative.

Starting at just £89.99 (including FREE before and after OBD Diagnostic tests) our Carbon Cleaning method is the least expensive.

The advantages are:-

  • Our Mobile Carbon Cleaning Technicians come to you
  • Potentially no expensive parts
  • No disassembly is required so no expensive labour
  • Completed in just 30 minutes so no having to leave your vehicle with the professionals
  • We are fully insured to compete this service at roadside or wherever your vehicle is located

As a preventative measure against dirty lambda / O2 sensors we recommend treatment every 15,000 miles

Thanks to the specially designed hydrogen treatment CarbonCleaning is the breakthrough alternative eliminating the need to replace expensive parts.

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