I have a 2000 F150 with a 4.6 motor. When it gets cold the CEL comes on with code P0125. Once spring and the warm weather comes back the CEL goes away until the next winter. I have already changed the t-stat a few years back. Any ideas????

 

i just went through two t-stats before i got one that actually opened at the 192 degrees they were rated for. i highly suggest you try that again. i had the same condition. both the original t-stat and the first replacement opened at 165 even though both were marked 192.

 

^^^ Exactly.... went through this same deal on my old Explorer.... My advice? get a Motorcraft stat.

 

I used my code scanner to read real time data and it says coolant temp is 156'F. How do I know if it is the t stat or the coolant temp sensor?

 

Well, you don't, but i'd put money on it being the t-stat... even if you recently replaced it. take it out and test it in boiling water on your stove. use a meat thermometer to monitor the temp of the water. you'll see it opens way too early.

 

I'm gonna get a Motorcraft t stat. I'ts amazing that the O ring is so expensive. Do I need to use a Motorcraft O Ring as well?

 

The Motorcraft stat I got came with it, but just using a FelPro/Victor Reinz/Whatever will work.

 

Agreed, any ring will probably work as long as it fits. My Motorcraft t-stat did not come with one, so i bought separately. I did pay the premium for the Motorcraft O-ring, though. The amount of $$$ I'm saving in fuel now that the engine actually gets up to temp will easily pay for the O-ring and the t-stat by the end of March, ie - $20 or half a tank of gas.

 

What is that new MC stat rated at? I am seeing they are rated at 192, but I am pretty sure the factory stats were 194.

 

Mine is 192.