BMW: 87, 325, temp gauge, catalytic converters

Question
Hi Josh:  I have a 87 325. The water temp. sensor with the purple top is broken, but the car is working ok.  I want to know if i have to replace this part immediately.

Thanks,

Answer
Ricardo,
 You dont "have" to replace it, but I would suggest it.  It's not hard to get to, and would take me 5 minutes to replace.  There are a 3-4 temps sensors on these cars, and one tells the electric fans to activate, one sends a signal to the temp gauge in the dash, one tells the computer when the temp is high enough to stop "cold start mode", etc...
 So if the broken one is for the cold stat mode, (thermo time switch) it will cause the car to run rich, and that could ruin the catalytic converters if left for a long time that way.  

 Hope this helps,
 Josh