Nissan Note 1.5 diesel, 10 plate, 25000 miles

following an engine service, the fuel consumption has gone down.
I was always getting around 61 - 62 mpg on my regular driving but now after service im getting 54 - 55 on same journeys.
any ideas what could caused this drop?

Regards

peter, September 2014

check to see if there is an air filter, it maybe missing causing the engine management to compensate in order for it to achieve the correct fuel/air mixer

RAZR, September 2014