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2019 Transit Connect XL Engine Coolant Over Temperature


CAD
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Here's another ongoing problem with this vehicle which happens everyday with two times in the shop and the dealer is unable to fix it:

Engine temperature gauge goes up all the way to high temp and  "Engine Coolant Over Temperature" warning appears on the screen - most of the time the warning does not lock in however there have been times when it did lock in and I had to "acknowledge" it.  For whatever reason the dealer has not replaced any parts such as the thermostat or sensor which brings me to a question:  is the coolant high temp detected through an ECT sensor or through a cylinder head temperature sensor or something else ?

Edited by CAD
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Since the van's computer is reading the temperature as high, the sensors for coolant and cylinder head are probably working. Or maybe not.

 

The cooling system has sensors for coolant temp, cylinder head temp, and transmission temp. The mechanical thermostat is the primary regulator.  Assuming that the thermostat opens, hot fluid flows to the radiator.  Assuming that the water pump is working, fluid cools and circulates back to the engine. Assuming that the coolant temp and cylinder head sensors are working, the electric fan should turn on as needed. Assuming that transmission temp sensor is working, a series of electronically controlled valves will allow cool radiator fluid to the heat exchanger. 

 

The thermostat could be stuck closed. The water pump could be broken. The fan could be broken. The fan relay could be broken. The fan may have blown a fuse. Check the fan connection. A mechanic may have forgotten to reconnect the fan. The car's computer could be failing in monitoring sensors and turning the fan on. 

 

Forscan could help with checking the sensors, and the fan. Old school thermometer to check hose temperature. If upper hose has fluid, and is hot, the thermostat opened. 

 

Make the dealership fix it. Try a different dealership. Escalate your concerns to Ford corporate. Van should be under warranty. Consult with a lemon law attorney. 

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21 hours ago, CAD said:

Engine temperature gauge goes up all the way to high temp and  "Engine Coolant Over Temperature" warning appears on the screen - most of the time the warning does not lock in however there have been times when it did lock in and I had to "acknowledge" it

When this happens what do you do, How long does it take to clear? Have you seen the data stream on a scanner?

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Fifty150:  Thanks for your reply, makes sense and I agree; I have been dealing with Ford Customer Service which started off great with a good rep now a different rep has been assigned - the response I am getting is no longer acceptable so I am not waiting another year for another waranty repair, already decided to go down to the court.

 

 

Edited by CAD
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GBL:   Mostly intermittent, frequent when starting the vehicle however will also happen while driving, clears by itself unless it "locks in" on the screen in which case I need to acknowledge it by pressing "OK".  I have not seen the data and assume that the dealer checked that.  However, since I do not believe they have done any actual troubleshooting whatsover, I doubt it.  While I am not an auto mechanic I do have a solid background in electronics troubleshooting and programming; the process of elimination to find the actual cause as explained by Fifty150 is the right way to go.  My non-auto mechanic opinion is it's a wiring problem, meaning something is loose or very quickly temporarity shorting out, grounding or it could be a faulty part - in my copies of the RO's there is no mention of any kind of troubleshooting at all by the dealer.

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7 hours ago, CAD said:

I do have a solid background in electronics troubleshooting and programming;

 

You have no way to reprogram this problem. At least I don't think that you do. It would require rewriting the operation strategy in the van's computer, in relation to the operating temperature parameters. I doubt that is your issue. 

 

Your van is reading temp sensors and turning the fan on and off as needed.  I doubt if those temperature parameters need to be reprogrammed.  It would be interesting to actually view those readings in real time.  The FORScan app will allow you to see temp sensor readings and the fan speed. That's a start. When the dashboard message comes on, see which sensor is actually reading a high temperature. Before you even open the hood, you can see if the computer is reading the fan, and if the computer shows that the fan is on.

 

Is coolant temp within 10° of cylinder head temp? It would be a problem if coolant temp was 200° & cylinder head was 250°.  Or if coolant and cylinder head were around 200°, and transmission temp  over 225°.   I want to say that coolant, cylinder, and transmission temp should all be under 225°. 

 

 Another thing to look for is if the computer shows your fan being on, and you lift the hood to find that it's not actually on.  Computer controls the fan, and thinks it's on. Look for a poor connection. Check the actual wiring harness.  Reason being that when the dealership replaced the transmission, the mechanic may have left it loose. Completely unplug the harness and look.  Are pins damaged? Is it burnt like it has been shorting out? Click it firmly back in place. 

 

Not that I don't trust your dealership tech. Have another dealership tech or mechanic physically look at the new transmission. Ask to have all the connections checked. It won't be the first time a tech installed a part, and left something loose or unplugged. Maybe a wire damaged. Broke some connection pins in the harness. Skipped dielectric grease. Or even pinched down a wire. 

 

8 hours ago, CAD said:

Mostly intermittent, frequent when starting the vehicle however will also happen while driving, clears by itself unless it "locks in" on the screen in which case I need to acknowledge it by pressing "OK". 

No reason at all for van to show overheating when you start the van.  I want to look for a temperature sensor failure. Or have a mechanic test the sensors. 

 

Suppose you have the FORScan app on, start van cold in the morning, and cylinder head sensor reading is high.....that sensor is faulty. 

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  • 2 weeks later...

I had an eerily similar issue a couple days ago. Turned out water got into the cylinder head temperature sensor connector, presumably causing to short and report maximum temperature:

 

https://fordtransitconnectforum.com/topic/8757-plugged-valve-cover-drain-hole-caused-cylinder-head-temp-sensor-to-report-overheating/?tab=comments#comment-34852

Edited by vanwerk
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