I have A4 2005 1.8T and after replacing engine and driving for a little bit both of my speedometer and tachometer errors dropped below 0 and when I drive they go up but dont show correct mph and rpm. FOr example driving 65 mph and it only shows 40 mph. and after both arrows dropped last week my mileage went from 58K to 54K all of a sudden. I don't know what's wrong thinking its electric/electronic problem. ANy help please?