Temperature light

[gibby]

Over the last five days my temp light has flicked on and off while driving three times, I've topped up the coolant and I've checked the fuse for the fan and that's ok and works. Is there anything else that might cause this or is there anything else for me to check ?? The car is not overheating and the oil temp is running normal.

[eyeletboy]

have you got braised hoses running across the engine for the fuel injectors?had this problem with mine.found out the braised hoses were rubbing on the rocker cover causeing a short with the temp light.

[gibby]

Thanks eyelet, I'll check that out tomorrow. 

[bosun]

I will take it you mean the red light in the temp gauge.If the gauge is reading normal its low water level low.If the level is spot on, then possible sender fault in the expansion bottle could cause this.

[rubjonny]

Can also point to incorrect antifreeze mix.  Next time it does it, take the plugs off & bridge the pins, if the light still doesn't go off you have a wiring problem.  If it does the sender has had it

Take it out and give it a good clean then see how you go.

[AudiA8Quattro]

How does the sensor measure anti-freeze concentration?
Thats a new one to me ?

[rubjonny]

It changes the conductivity of the coolant mate

[AudiA8Quattro]

Ok, never seen that happen before.
I'll just have to take your word for it 

[AudiA8Quattro]

How it actually works is the sensor has to metal prongs that go in the water, water conducts, so this makes a circuit, light stays out.
If water does not cover the 2 prongs then no circuit so light comes on.
I don't think it has anything to do with antifreeze concentration 

[rubjonny]

Antifreeze

Antifreeze is a substance which lowers a solution?s freezing point.? It removes ice or prevents ice from forming.? It also prevents freezing in planes and automobiles. Antifreeze is also used in refrigerants and as heat-transfer fluids.? Ideal antifreeze should be chemically stable.? It has low viscosity and electrical conductivity and a high boiling point.? Automobiles operate at an extreme temperature, therefor it is cooled by liquid that circulates through the cooling system.? Antifreeze is noncorrosive and has good heat transfer properties.? Most antifreeze is used in cars today.? It is composed of methyl alcohol, ethyl alcohol, and ethylene glycol.? Also most antifreeze have phosphate nitrate, or another anticorrosive agent.? Some time ago kerosene, honey, salt water, and methyl alcohol were used as antifreeze.? Automobile antifreeze is a well-known poison.? The sweet taste appeals to most animals, like cats and dogs.? Consuming even a small amount may result in death for small pets.