EGR cooler failure seem to send the coolant to #8 and then you have some real problems...so yes proper coolant maintaince is a must.

 

But unlike the 6.0L trucks where the EGR cooler is plumbed in series with the oil cooler, the 6.4L cooling system plumbs the two in parallel with each other. So a plugged up oil cooler shouldn't fry the EGR cooler, unlike a 6.0.

 

that was a better answer!

 

UPDATE: I have an upcoming appointment with local Ford dealer to diagnose problem on P012F including how they plan to fix in great detail- -how to flush properly and install new oil cooler. Information on how to properly flush is readily available and I have seen many threads on how NOT to do it. Kinda scary that there are quite a few threads that bash the Ford dealers--so my alert level is high and trust level is low. Just setting up the appointment ended is a discussion bashing the 6.4 and recommending DPF and EGR delete.

 

I thought my oil cooler was bad, but the coolant had an air lock somewhere or something, and when it finally got figured out, the oil cooler numbers are back to normal.

 

That would be a great outcome if I did not need a new oil cooler. Fingers are crossed. Installed Edge CTS this weekend and within 10 or 15 minutes, the ECT was hovering in the 194 range while the EOT steadily increased to 217 without any hard driving. Usually takes 20 minuets to throw the wrench and I have not been able to drive for 20 minutes to see the temp delta between ECT and EOT before the wrench comes on. Will do that today. I have been reading it is 15 degrees but I have been at 20 degrees with no wrench so far.

 

Spent some time driving for about one hour in the mountains of NC yesterday. Air temp was 70 to 75. EOT rose to about 20 degrees above ECT and stayed in that range except for when we hit some moderate hills. ECT rose to 198 and EOT rose to 228- -20 degrees. After about 20 minutes at this differential, the wrench light came on. Max temp diff was maybe 22 degrees. Taking to dealer ship tomorrow.

 

don't clear the code.

 

10-4. Will not clear the code. THX!

 

Dealer still has not isolated problem causing P012F code. Could a bad T stat (or both) be the culprit? Could someone help explain that?

 

Hey, first post here. I have an 08 with a Mini Maxx tuner and am seeing 195-205 ECT and up to 240 EOT. I am not getting any codes or the wrench. Has anyone seen this happen before?

Thanks,
Jake

 

Have you had latest flash 11B23. I had flash done on my truck and computer saw 30 degree differential and put truck in limp mode. Ended up needing tstat and oil cooler

 

I'm not sure, I've only had the truck since Feb. How do I check what the flash rev. is?

 

I also have not had the truck go into limp mode.

 

Final Thoughts: Replaced both T stats and flushed coolant system, the correct way with VC 8 and 9, etc. Error code cam back, so had to replace the oil cooler. Unlike previous owner, I will maintain coolant system the way it should have been all the time.

Thanks for everyone's comments. ECT and EOT are now running a max of 5 degree delta.