Hi,
Wondering about what to do.
This light is on but was not until I fixed the throttle housing. I am wondering if alot of air had been let in before in order to cool the engine, thus making sure the temperature light didn't come on. Could this be so. Deisel 1.9 2001 model. I just bought it. The throttle housing being broken there was a lot of oil to clean but no light problem until now with it generally sealed up again elsewhere too where air manifold was loose in places.
Maybe the water pump does not work etc but just wondering about experience of this if the light had not been coming on before. It is very hard to believe the air cooling of the throttle in a more closed environment made the difference to the temperature gauge or is that where is, in that housing area.
Thanks in advance and hopefully later too.

 

I'm not familiar with the diesel variant (don't get many (any?) of those in the US), but yes, low coolant level can keep the high-temperature light from coming on, since the sensor isn't submerged in coolant.

With any overheating problem, the problem could be the water pump, the thermostat, or a blocked radiator. Hard to say which without some troubleshooting. I believe that the thermostat on your car is probably VERY easy to swap out, or even to just remove (if you remove it AND it was the problem, the engine will no longer overheat, but it also won't come up to proper temperature). With the thermostat out, you should see plenty of coolant flow if you take off the radiator cap. If not, you may well have a blocked radiator.

 

It seemed unlikely always to be coolant to me but I had to consider air bubbles etc. Turned out to be wiring. Thanks for the input.