I have a 05 Expedition that is throwing a P1289 code. This is has been a real puzzle. It first threw a P0119 code and the temperature gauge would bounce around and then level off to normal, a couple of minutes of driving and it would do it again. At that time I replaced the ECT sensor. It did not fix the problem. I then changed the thermostat and flushed the coolant system and added new coolant and it was still throwing the same code. I then replaced the pig tail to the ECT sensor because the bare wire was exposed. Now I have a P1289 code along with the display reading "engine temp data error" and the AC does not work. The car seems to run fine, it is not blowing smoke or running rough or it is not difficult to start. Has anybody had this experience? Any help would be great, as I am looking at $1300 estimate at the shop.

 

Code P1289 is for the cylinder head temperature (CHT) sensor, not the engine coolant temperature sensor (ECT). The CHT is under the intake manifold.

 

Here's a video of replacing the CHT sensor without removing the intake manifold. You'll need a Gearwrench 19mm flex head wrench .

 

Thank you for the video. I have replaced the CHT and pigtail to the CHT, the sensor on the oil pan and the thermostat. I am hoping for some help of where to go now.

Does the PCM need to be reprogrammed for the new sensor?

 

Do you have a OBDII scanner capable of reading live data ? What engine temperature does the live data show ? Is it jumping around like the instrument cluster gauge is ? Or is it a fairly steady temperature readout?

 

OBD II scanner has a constant temperature of 13 celsius. The gauge pin has dropped to cold and does not move.
I have an after market sensor in there now and have order one from Ford, I hope that this is the issue. My next step would be to might be a
new CHT sensor wiring harness. Has anyone had this issue?

 

I have this issue. I replaced the cht sensor, but am getting the 1289 code again. My gauge on the dash does not read anything. My scan tool reads 55 degrees F for the coolant and doesn’t budge even when the engine temp is rising on the scan tool. Did you find the solution?

 

It could also be the sensor pigtail or any other part of the wiring harness that contains the CHT sensor circuit.