we are looking for CO2 (or O2) sensor to measure the CO2 in a gas boiler to control the lambda of the hexaust gas to keep the lambda constant during combustion. The max temperature in the application is 120°C. the used gas is the G20 family (natural gas) and the GPL family. The life of the sensor has to be 10 years. The hexaust gas does not have particular polluting materials (no lead, no oil,…).