Returning home on Monday by motorways and A roads I became aware that the speedo appeared to be reading significantly SLOW. I checked against my GPS satnav and confirmed the speedo was reading a constant 9mph slower than the GPS. Even
noticed. This error was constant for various speed between 30mph and 70mph for a good 20 miles. I stopped and restarted the engine and the speedo corrected itself to around 2mph above the GPS reading which I guess is about right.
Has anybody else experienced this? Its easy to spot a 9mph error but if it was 5mph I may miss it but the ugly yellow box on the lamppost would not. It's never happened before although the rev counter sometimes sticks at idle revs when I turn off the ignition.
"But honest officer the speedo said 30......"
