Hey everyone, I have a 2000 Excursion Limited with a 6.8L. I'm having an issue with my CHT... I've replaced it 3 times now. I've also replaced the thermostat and flushed the coolant. With that being done the only thing left is checking the wiring to check for a break or a bad ECU... does anyone have or can lead me to a wiring schematic. And if anyone has had this issue before what was your outcome? I appreciate your time

 

What is a CHT?

 

It's the cylinder head temperature sensor..

 

What is the issue you are experiencing? Bad readings, no readings, hi temp??

 

Ok... long story but here we go..... I first noticed a ruff idle and the ac stoped blowing out cold air.... hooked up the code reader and I go a misfire code and P1289... ("cht" high input) so I figured out that the clip for the fuel injector wire on cylinder one was broken and came off so I replaced the clip and replaced the CHT sensor, the AC started blowing out cold air right away..... a week later it stoped blowing out cold air again so diagnosed again and there were no active codes but there was the p1289 on the memory codes. So I cleared the codes and relaxed the CHT again... cold air far about a min thin warm air again.... diagnosed again and there are still no active codes but I'm getting a memory code of p1289 and I'm running in limp mode and my AC will not blow out cold air... so I've been going through what the trouble shooter to fix the p1289 and nothing has worked yet.

 

I keep getting a P1289 code. "CHT high input" I've replaced it 3 times now.... I've read that it is just a false overheat code but I'm still running in limp mode and it is causing my AC not to blow out cold air. The weird thing is, the p1289 code is not comming up on the active codes it's coming up under the memory codes and it keeps comming back after I clear all the codes.

 

I feel like acronyms should be spelled out the first time they are used. I thought, what? when I saw that too.

Only time I ever got a cylinder head temperature code was when the little heater AC thing broke and blew all of my coolant out. lol

Might be a stupid question, but what kinds of engine temps are you seeing before it goes into limp mode?

 

did you ever figure this out? I"m getting that code as well, but the engine isn't overheating.

 

I've never messed with this, but just thinking about it logically here. If you've replaced the sensor, and reset the codes, and everything works fine. Then it trips again, it sounds like you have a short/grounding problem. If you can verify the engine is indeed not getting hot that is.

Examine the wire the best you can for any rubbed or pinched spots. If you have a good meter, check the wires for continuity.

edit: just realized this is old, but maybe it'll help Kai.

 

Agreed. i need to get my laser thermometer out and check actual head temp when this is going on.