Planning the next
AO Silver Member
Join Date: May 2007
Location: United Kingdom
If you have a multimeter, it's easy enough to test the temperature sensor.
If you do have or have access to a multimeter try this :
With the car cold, measure the resistance across the sensor. With an ambient temperature of about 20°C, the resistance will be in the range 2280 to 2720 Ohms. However, the exact temperature doesn't matter because the next thing you do is measure the resistance across the air temperature sensor in the intake pipe between the expansion tank and the thermostat. The two figures should be very similar. If they are, your water temp sensor is OK at low temperatures.
The next thing is to allow the engine to get hot ( reconnect the sensor before you start the engine as you don't want the ecu warning light to come on ). With the engine hot ( 80°C ) shut it down and again measure the resistance across the water sensor. The resistance should now be around 300 Ohms. You won't get those figures of course as you're working from the temperature gauge, but if the figure you get is close, it is unlikely to be the water temperature sensor that is at fault.