Forum:
So my speedo played up a few times recently- registering half the speed that I was actually doing after an hour of being on, but then it would be fine if i turned the car off and on again. Today on the dual carriageway it said I was doing 120mph which I know is wrong as firstly, it's a fricken 1l charade, and secondly i use an app on my phone to give me speed readings and that said 67mph.
All of a sudden the speedo wouldn't go below 80 and wouldn't reset to zero even after turning the car off. So now the car can sit there with no keys in the ignition and think it's doing 80.... What the hell happened and what do i do?
Hi. First thing to do is
Hi.
First thing to do is check the Connections on the back of the clocks. Shouldnt be a big task taking the clocks out of the dash.
if the 3rd party device plugged into the ODB-II port is also acting up then you know it's not the clocks but either a fault being detected on the ECU or something in the ECU module that has developed a fault or some sort of speed sensor fault. Ideally you need a wrirng diagram to find out where the speed sensor is located.
Secondly to check that the ECU is working correctly try and get hold of something like a Scangauge-II or something similar, which can be plugged into the ODB-II port and as one of the gauges should be a speedo to check that the ECU is registering the speed correctly. If it is then I'm afraid it the clocks that are playing up
Good luck
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'12' Plate Mazda MX-5 2.0 litre NC 3.5 Venture Roadster 160BHP
'15' Plate SEAT LEON 184 FR TDI. 240BHP/500nm Torque.
Past: '53' Plate Yellow YRV Turbo Approx. 150BHP