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Discussion Starter · #1 ·
Going for a long shot here:
Why does the vehicle continue to show overheating condition?
2014 Ford Escape 1.6
Both the engine and coolant temperatures sensors changed, wiring checked, fans, thermostat and water pump working. Maximum coolant temperature when I can keep it running a few minutes is 170F. Computer reset. Coolant full. Code P1299 continues to display and goes into "Fail-Safe Mode" within a minute of starting.
 

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No other codes? Do you have a scanner that shows what it think the temperature is? The sensor you changed was the cylinder head temperature sender, that pushes in and is held with a clip, and not one that screws in, right?

I think that sensor is a common failure point. It causes the vehicle to go into failsafe mode, won't rev up and will only idle/5 mph drive. Often times they leak and the coolant causes the connector to either corrode or just not make contact or to be bridged. Seems like it might be a little harder to get to than the Fusion, mainly due to the cowl (which on the Fusion the cowl is in the way of a lot of stuff unless you have the 2.5).
 

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Discussion Starter · #3 ·
No other codes. Both the coolant (push in) and cylinder head (screw in) sensors were changed. The scanner says my coolant temperature maxes out at 170F. Oh, they are, definitely, not easy to get to! We've "burped" the coolant system, too.
 

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Given the sensors have been replaced, I would start looking at the wiring harness. Logically the only way a sensor could 'peg' within that short a period of time is if the 5v reference was in contact with the 'sense' line, or similar. To my knowledge, temperature sensors or senders do not have 'heater' circuits, so the only way they could be reporting overheat is if the were being supplied a signal from another source.
I do not have access to the wiring schematic, but a physical exam of the wires and knowledge of any reason for the wires to have been damaged(service/accident/watered/drowned/cooked) may bring an aha moment whey you remeber the alternator being replaced(e.g.) and the mechanic being in a hurry.... build your own.
Anyway, I would look at the wiring, the PDB, and any points where you think corrosion or pinching could have damaged the insulators, etc.
tom
 

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Discussion Starter · #5 ·
Given the sensors have been replaced, I would start looking at the wiring harness. Logically the only way a sensor could 'peg' within that short a period of time is if the 5v reference was in contact with the 'sense' line, or similar. To my knowledge, temperature sensors or senders do not have 'heater' circuits, so the only way they could be reporting overheat is if the were being supplied a signal from another source.
I do not have access to the wiring schematic, but a physical exam of the wires and knowledge of any reason for the wires to have been damaged(service/accident/watered/drowned/cooked) may bring an aha moment whey you remeber the alternator being replaced(e.g.) and the mechanic being in a hurry.... build your own.
Anyway, I would look at the wiring, the PDB, and any points where you think corrosion or pinching could have damaged the insulators, etc.
tom
The only other work that has been done on the vehicle was the speed sensors at the rear wheels. I'm not sure what you mean by "PDB." I grew up working on cars, but when the electronics came along, the backyard work ended.
 

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Does it immediately at key on show it is overheating and in fail safe mode, or does it have to heat up then go into that mode? If you clear the code does it immediately come back? Sounds more like a wiring/connector issue than the vehicle actually overheating.
 

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Discussion Starter · #7 ·
No, Sir. It runs for approximately a minute, the fans turn on at a fast speed, then the temperature gauge swiftly goes up, the overheating light comes on in the information display, and it, then, goes into faii-safe. Code 1299 re-appears on the scanner. The temperature, on the scanner, reads 170F.
 

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PDB is Power Distribution Box. The under hood box that has all the fuses and relays with power and ground connections and wires out to all things in the vehicle. If you live in an area with salt conditions, sea spray or road salt, you may have stuff going on underneath said box.
The time delay from start up to overheat likely is how long it takes for current going through the sensor to reduce/increase the resistance. PTC - positive temperature coefficient - or negative - either way the resistance changes with temperature, which is good, but it can ALSO change if current is caused to flow through the resistor above and beyond that which it is designed to work with. If you have a 5V PTC, and you feed it 12V accidentally, the PTC will show cooking temperature when it is not true because you have current flowing with a 12V push rather than a 5V push, so more current will flow... and cause more heat from resistance blah blah blah. Only real point is to examine the wires and V values at the connections to the temperature sender(used by the computer). The sensor is used by the temp gauge. I think.
If the cluster has any other weird or unusual readings, such as a fuel gauge that reads odd, it could be the voltage is not being limited properly. Old Fords had a voltage limiter/reducer mounted to the backside of the cluster to give gauges a closer to consistent voltage. The gauges would give unusual readings when the limiter broke. System voltage varies from startup of ~10v+ to 14.5+ when charging. A meter will give various readings when its 'base' voltage varies by ~4-5V, so you cannot depend on the gauge reading being consistent. Limit the gauge voltage and viola, mo bettah readings. If they still have them, it could be failing. I do not know how Ford gets the 5V base reference.
tom
 

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I think I might have them backwards, as the clip in one goes into coolant, and CHT usually measures the actual temperature of the aluminum head.

I added the Ford PIDs to Torque and I see both independent sensors with different values (this is after 45 seconds of running, but ambient temps are 105 so doesn't take long):

I am rebuilding my displays, so I don't have a great looking dashboard like I used to have, and there are some differences between my completely different generation cars, but Coolant is the built in one and uses ECT< and CHTMP is the Ford specific one you can add as a PID and with the calculations.
 

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I may have this wrong, but I think the 4 banger has a sender right in the middle of the cylinder head between two spark plugs. You can watch a video by makuloco about replacing that sender, as they are subject to corrosion and failure. I do not remember the symptoms, but he did go through the process and I believe showed how the sender looked upon removal. He may have had a 'trick' he used to clean up prior to installing the new sender. It's been a while, and I don't own one.
Have you looked at OBD-II information? A plug that will work is not expensive and FORSCAN software, for an andriod or ipad/iphone, or for PC is free. You can get USB connected devices or Wifi or even bluetooth.
tom
 
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