I received an invitation from Peugeot asking me to bring a 2018 naturally aspirated gasoline engine Peugeot 208 (61 kW) to the workshop for a firmware update fixing lamba sensor management which otherwise results in higher than allowed NOx emissions.
What effects should I expect as result of such update?
Lower max torque (and therefore power) and overall higher fuel consumption (due to a richer mixture), only lower max torque, or only higher overall fuel consumption?
I wonder whether I can, if desired and meaningful, refuse the update.
Edit: the reasoning behind is: if lowering NOx emission produced advantages from a driver or advertisement point of view, they would have done it in the beginning or they would have pointed it out very clearly in the letter. Since the change comes after the purchase and no advantages beyond emissions are listed, it will likely worsen some aspects that they expect me to care about.