High fuel consumption of my 156 has been puzzling me from day 1, the figure was about 100km/12.x liters or 22.6 mpg. It is high for a 2-liter engine here.

From a local Alfa fan club gathering, a friend suggested replacing the O2 sensors when we had talked about the fuel consumption issue.  I remembered that some discussions on car forums suggested something similar.

decaying o2 sensor causing high fuel consumption