2018 F150
2.7 L Turbo
132k miles

Last week the CHT threw a 1299 code. I replaced it. 4 days later the new sensor is junk again. Thoughts?

 

What brand did you go with? Purchased from where? People often end up with bogus parts from scAmazon and eBay. Stick with OEM and purchase from your local dealer or perhaps Rockauto.

 

I went with Duralast from Autozone. It was the only thing available at the moment. Just heard from Ford Service that they can't my truck in until the end of next week. Wondering if a better quality sensor wouldn't solve the headache

 

Have you considered that perhaps there IS an issue with the cylinder head?

 

Definitely. That's why I'm trying to get it into the dealer. Just seeing if anyone has experienced a bad or inferior sensor before

 

Code description is..................... low coolant, cooling system issue,
Is the engine in low power Limp mode?
Is it overheating?
Cooling Fans not running.
.
The sensor has to be torqued far enough in for the tip to touch the head casting, in a Blind hole.
Once removed it can't be used again because it pushes the tip back into the body and does not recover back outward.
If that happens it could set a voltage signal that reads like it's over-heating. The code may even have to be cleared after the new Sensor it put in place because the system can't tell if it is fixed or still faulty since there is no reference for it only the Sensor value it detects.
Sounds a little funny until you find out the Sensor is a special wide temperature range that has two elements and three leads to it..
Good luck.

 

Engine is in limp mode. fan runs on high instantly and the gauge pegs out immediately

So how does one know where to torque to? Man they screw up a good thing

 

Copied from another thread. The DTC will NOT clear itself, you MUST clear the DCT with a scan tool. From the 2015 2.7L Ford WSM the following below describes overheat condition.
Closed Loop Mode (one of the two cooling monitoring system modes-this is full description from WSM)
Stage 1 of the strategy commences if the engine starts to overheat. The CHT sensor transmits a signal to the PCM, which moves the temperature gauge pointer into the red zone. If the engine is not switched off and the temperature continues to rise, the Powertrain Check Lamp is illuminated. This indicates to the driver that the engine is approaching critical limits and should be stopped. At this point DTC P1285 is set in the PCM which can be retrieved using a scan tool.
Stage 2 of the strategy commences if the lamp and temperature gauge are ignored by the driver. The PCM will start to control the engine by cutting out 3 cylinders and restricting load. The RPM will be limited below 3,000 RPM initially then will slowly be ramped down with time to as low as 800 RPM. Simultaneously the MIL illuminates. This indicates that long term engine damage can occur and vehicle emissions will be affected. At this point DTC P1299 is set in the PCM which can be retrieved using a scan tool. Air is drawn into the deactivated cylinders. This helps to control the temperature of the engine internal components. The deactivated cylinders are alternated to allow even cooling of all the cylinders. NOTE: If the driver is using a high percentage of throttle travel (for example, an overtaking maneuver) when the PCM starts engine deactivation (Stage 2), the deactivation will be delayed for 10 seconds. NOTE: After 3-cylinder operation has begun, the engine will not revert to 6-cylinder operation, even if the temperature should fall, until the ignition is switched off and then on again.

NOTE: The MIL can only be extinguished by using a scan tool after the fault has been rectified and the DTC cleared.

Stage 3 of the strategy will commence if the engine temperature continues to rise. This results in the engine being totally disabled before major engine damage or seizure occurs. The Powertrain Check Lamp will begin to flash, indicating to the driver that the engine will be switched off after 30 seconds. This allows the driver time to choose a suitable parking place.

The CHT sensor is ONETIME use only. Do not re-torque, loosen or otherwise mess with. Simply (COLD ENGINE) - old out -new in - torque to 106 lb-in. (12Nm). No thread lube. Clean the hole on cylinder head ONLY with compressed air. Got my replacement from Rock Auto.

Just replacing the sensor does NOT fix any cooling system problems if they are present!!

 

.
Yes, read Home 2#7 reply.
The 'scheme' of it is to be sure the driver does not damage the very expensive engine by just keep driving it until there is permanent damage and to >be sure< the repair has fixed the cause of the issue.
Good luck.

 

[/QUOTEThese are not our father's trucks anymore. Throwing parts at them with no other knowledge is a "no-no."