Lambda sensors

A lambda sensor is a sensor which is located in the exhaust of a car with a petrol or diesel engine. The probe measures the proportion of oxygen in the exhaust gas and transmits this measurement to the engine management system. The lambda value is an indicator of the effectiveness of the combustion. Depending on the lambda value, this is adjusted by the engine management system through a modification of the fuel and air ratio composition. This is done via the fuel injection, by changing the injection time of the injectors.

All modern combustion engines have one or more lambda sensors in front of the catalytic converter and one or more lambda sensors after the catalytic converter. There is a regulating sensor in front of the catalytic converter and a measuring sensor after the catalytic converter. The ECU receives data from the lambda sensors and adjusts the injection accordingly. The measuring sensor, after the catalytic converter, checks that the catalytic converter is working properly. If the catalytic converter is defective, the measuring sensor will detect this and illuminate the engine malfunction indicator light.

Lambda sensors last approximately 150,000 - 180,000 km. When this is old or defective, the engine malfunction indicator light will usually come on.

NOx sensor

The NOx sensor is placed directly behind the catalytic converter in the exhaust to monitor the harmful NOx emissions. These exhaust gases develop at high combustion temperatures and are harmful. When the NOx sensor measures that the emission value is too high, it will signal to inject more AdBlue or more fuel for a richer (and cooler) combustion. If this sensor is defective, the engine malfunction indicator light will illuminate to provide a signal. If you have any questions or would like advice, please contact our product specialists. They will be happy to assist you.