| from: [ http://www.pexcom.com.au/z32cms/e107_plugins/content/content.php?content.398 ] The cat over temp warning light is triggered by the two sensors just after the catalytic converters when they read a temperature which is too high. This is typically caused by unbrunt fuel entering the cats and burning in there (rather than in the cylinders!) and the light is triggered. This suggests that either too much fuel is entering the combustion chamber or there is not sufficient spark to ignite the fuel, and it is making its way unburnt to the cats. As an example, when a spark plug or PTU fails and the car is only running on 5 cylinders, the cat temp light will usually come on sooner or later. The cat temp sensor's ONLY purpose is to trigger this light, no changes to the engine management come into effect. Often with aftermarket exhaust systems the installer will be too lazy to include points for the cat temp sensors, and they will either be cut off or hanging there. While they are not critical and many live without them, they are nice to have and the light is there for a reason. It would be difficult to do serious damage unknowingly driving around with unburnt fuel in the cats, but doing this for weeks on end would probably not be good, and would certainly be hurting performance and fuel economy.
|
