my speedo shows 70 mph when standing still, when moving it shows 55 mph. with engine turned off it still shows 70?

tony, August 2010

Check your handbook. If it's a modern vehicle it might use the speedo as a diagnosis device. My motorcycle (YZF600R) uses the rev' counter (Tachometer) to alert the user of any faults in certain components eg: 3000 rpm = Throttle Position Sensor, 8000 rpm = Fuel Indicator Light.

So check the vehicle handbook/manual and you might get lucky.

Mr Smith, August 2010

It would be helpful to know what vehicle you are talking about Tony.

Concerned Parent, August 2010