If its true what is the correct coolant temp sensor i need?

Hi, i have an 89 e30 325i, im on a quest to solve the idle problem. When i found out this DIY article it made me realize it's almost same problem as im having. When the engine is cold, that's the time the idle drop and rise. It smooths when engine is warm. Also, i have CEL 1222 on idle and gone when revving up. I replaced vacuum hoses, icv, icv hose, intake boot, o2 sensor. I just bought the FAE coolant temp sensor part #12621710512. I read some comments above that its for temp gauge. If its true what is the correct coolant temp sensor i need? Please advise. Thanks!

__________________
This post was auto-generated based upon a question asked on our tech article page here:

[Kerry at Pelican Parts]

Call one of our parts specialist at 888 280 7799 and they'll help you get the CTS you need

- Kerry