FUEL CONSUMPTION
 by Jim Wilcox
Have you found your fuel consumption slowly increasing over time ? Has your vehicle done more than 100,000 Km? It may be time to replace your- - - - OXYGEN sensor. This poor little sensor/sensors reside in the exhaust pipe just after it comes out of the engine and measures the amount of residual oxygen in the exhaust gas. The computer uses this information to inject the correct amount of fuel for each combustion cycle. Over time the sensor gets carboned up and also loses response to the oxygen and the computer now getting an incorrect signal adds extra fuel to the cylinder, which is now not running at optimum mixture, and up goes the fuel consumption. The sensor has not failed altogether so the check engine light does not come on as the computer is still getting a signal. Going over East last trip I only got 8km/l going over, changed the sensors while there and got 10km/l coming back with no other changes to the Outback. It had done 150,000Km

Introduction to Oxygen Sensors