I have a 1990 maxima. When I'm in park or even in drive mode while breaking, the speedometer never goes down to 0 at a complete stop. It always go back and forthbetween 9 mph - 15 mph. The milage also goes up on it's own even when not driving. Its as if it thinks the car is still moving when I'm only idling or at a complete stop. I'm not sure what's wrong, I don't want the milage to go up when I'm not even driving. It's gonna make re-selling harder. I already have 190k milage on it. Has anyone had the same problem and was able to fix this? Can anyone help me? Any help is appreciated thanks.

 

Take it out, clean connectors. Theres a short circuit causing current leak to the gauge wirings (between sender unit at tranny/instrument panel). Clic on link below, read through

 

it sounds like your speed sensor is bad.