@TechConnectify Superb vid! But I have an issue with the claim at 24:28, that three way catalyst converter cannot work at lambda equal exactly zero. Below is graph of three way catalyst converter efficiency. Solid lines are for harmful exhaust components after the catalyst converter (dashed - before). Hatched region is "catalyst converter high efficiency region". As you can see at lambda=1 CO, HC and NOx are all low. But the 2 state lambda sensor is, well, 2 state. It cannot show when you are at lambda=1. Even wideband lambda sensor is nothing more than 2 state sensor with an oxygen pump added. And you are using current to pump in or pump out oxygen from a some "semi-closed" volume in the sensor until the state changes. This might be a reason for small oscillations even with a wideband sensor. Source of the graph "Podstawy budowy silników - Sławomir Luft"