The lambda input can be used for either

Lambda 1 control using a 3 or 4 wire sensor, allowing the user to set up their engine for MOT or SVA purposes.*

or

With the use of an external wide range lambda system, you would then be able to program the ECU by using a self-learning mode. Lambda targets can be set within the ECU according to speed & load to suit your engine.

*Please note to obtain SVA or MOT test passes you will need use a catalytic convertor. We would recommend the use of a high-flow motorsport cat in order to not compromise the performance of your engine.