Join Date: Feb 2007
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As you say the stated earth point seems to be quite a distance from the dash. In my experience most cars have an earth point around the right hand front footwell.
I also would think if it was a duff earth problem it would affect more instruments on the dash.
Have you tried wiggling the wiring loom that feeds the temp sender to see if it has any affect an dhav eyou checked what voltage is going to the sensor.
Currently in madnoel10's garage:
Honda Civic 1.4l