The "current" fuel consumption displayed has become very sluggish in my 2.0D engine. When I take my foot off the "gas", even coasting downhill, the displayed fuel consumption remains high for at least 100 meters/yards.

This behavior is in sharp contrast to earlier when the display would snap to "0" almost immediately. I don't notice any drivability issues and average fuel consumption is the same ... Year after year suspiciously consistent at 5.7 liters / 100 km !

I can look at live sensor data, e.g, fuel rail pressure, or scope the sensors themselves but don't have any experience interpreting diesel fuel systems.

Thanks!