The Lambda sensor on our car has failed, causing the EML (engine maintenance light) to come on. So the car is going to the garage today to be repaired. We know it is the lambda sensor, because the EML light came on before we had it serviced 2 weeks ago, and after repairs it went off. But not before a car computer diagnostic revealed a problem. The garage said that if it came on again, we would need to get it fixed.

Although the car is not behaving strangely, we are going away for a long weekend to the west country, and we don’t want to have any problems when we are down there.

But what is the lambda oxygen sensor?

The exhaust gas oxygen sensor (EGO or O2), or lambda sensor, is the key sensor in the engine fuel control feedback loop. The computer uses the O2 sensor’s input to balance the fuel mixture, leaning the mixture when the sensor reads rich and richening the mixture when the sensor reads lean.