The dash temp gauge will not move even when engine is turned off, it stays at 280. Checked the thermostat, radiator cap, hoses, no leaks on the water pump and no strange noises. What could cause this problem and how do we check the gauge to see if it still works?
temp gauge pegged out on 1994 Oldsmobile Achieva
Disconnect the temperature gauge sender unit at the engine and see if the gauge now goes to rest, it sounds like a bad sender unit or shorted to ground wire, The temp sender is between the ignition coil packs and the valve cover the wire is colored dark green.