I'm a little confused and hoping y'all can help. My truck is not throwing a CEL anymore but it does keep a pending code for P1289 which is the cylinder head temperature sensor.

So I have a 1997 Ford F150 with the 4.6 Romeo in it. We just replaced it 2000 miles ago with the same engine out of a 1998 Crown Victoria. and I have noticed that right in front of cylinder 5 there are 2 wires that aren't connected. One that is connected to something under the intake by cylinder 5 (which I assume is the cht) but isn't connected to the wiring harness and can't find a spot where it looks like it will connect. The other comes off the wiring harness and is very short but also doesn't connect to anything. And they won't connect to each other.

Autozone tells me I don't have this sensor per my truck but the dealership will sell me one. The dealership also says its next to cylinder 4.

Is it possible the Crown Vic does have it but my F150 wiring isn't set up for it? And if that were the case why would the code pop up for it? If this is true what will hurt if anything if i just leave it the way it is. Also what is it supposed to connect to at the wiring (not the sensor connection side) end if I am supposed to have it?

Also I still have a slight miss or hesitation but nothing major and my fuel economy sucks... Could this cause it?

I really appreciate y'all's help as my Haynes book and Ford disc don't go this I depth with it and thanks to a script issue I can't pull up the wiring diagram on the program.

 

Oh I should probably also include my ac works perfect and my temp gauge doesn't ever even reach the halfway mark which is how it was before the engine swap. I know these are common issues with this sensor but I'm not having them.

 

So I wanted to let yall know that I got this fixed and no more code. I ended up taking the connectors off, stripping the wires, and soldering them to each other. The color of the wires matched so thought why not just eliminate the connector part of it lol. Needless to say I dont have the DTC code anymore

 

I am not 100 percent sure on this but I believe these are the engine coolant temperature sensor and the engine temperature sending unit. These are both located at the manifold. The sensor sends the temp to the PCM for monitoring and controlling engine performance. The sending unit sends the temperature reading to you temp gauge on the dash. These may be in different locations on the engine from the crown vic.

 

They were for the cylinder head temperature sensor. I could deer it by number 5 if I looked real good once I took the intake tubing off.

Thanks for the replay though.

 

97-98 F150's with the 4.6/5.4 actually have 3 temp sensors where the 99+ 5.4, and 00+4.6's only have 1. The actually CHT is located on the outer exhaust side of cylinder #5. The 2 other sensor are coolant temp sensors. 1 coolant temp sensor works along with the cht where the other is just a ECT. So the one that was unplugged was the right one. You should have just soldered the wires together tho. It can make the truck run really rick because the PCM will see that the CHT is -40* while ECT will tell the PCM it at operating temp and will never go into closed loop. Only reason I know this is because my truck has a PI head swap, and intake swap and had the same codes and did the same thing until I had it tuned to remove the CHT sensor in programming.

 

Thanks for the response. I did solder the wires together about a week ago and so far so good so it seems to have solved the problem. Just wish it would have solved the other ones along with it lol.

 

I would definently want to check PCM data to see what it thinks for temperature. If the truck thinks its minus 40. May cause these other problems especially fuel mileage. You got rid of the check engine light because there is no longer an open circuit. There is a patch harness that goes from the main wiring harness to the sensor. Is located under the intake by #5 cylinder. The patch connects near the thermostat.

 

That's pretty much where these two were that I connected. I'm not worried about it right now as my dreadful misfire and the cause of that is foremost on my mind. It has also never overheated and the AC works fine and I here these are two common issues if the CHT IS bad.