The Lambda sensor (also known as the oxygen sensor) monitors oxygen levels in the exhaust system, helping to achieve the right fuel to air mix and regulate harmful gas emissions.
A lambda sensor usually has a life span of up to 50,000 miles but this can be dramatically reduced if the sensor gets clogged up or contaminated. A oxygen sensor gone bad can cause increased fuel consumption, poor driveability and MOT failure due the vehicles high emissions readings. You also risk damage to your catalytic converter which is a far more costly repair. In most cases, a faulty sensor will trigger the check engine warning light on your dashboard.
If your lambda sensor has reached the end of it’s life cycle, it can be easily replaced at low cost but it is advisable to use a qualified mechanic.