High temperature fault car won’t start

[Chrissyw]

Hi guys .
ford fiesta 1.4 zetec petrol . Car had drove no issues . Parked up for two weeks, went to start it and wouldn’t start. Engine not turning over all usual lights on plus engine warning light. Display said . High temperature warning engine fault.
I have checked all fuses and all ok .
has any one had this issue ?? If so what was the remedy? Thanks in advance.

 

[Handy Andy]

Sounds like the sensor (you have two) one either to tell the system the temperature - or the other one to turn on the high-speed fan (overheat) is either shorted or failed open.

The dash should be able to tell you the TEMP when the key is turned to ON but not to Start.

Battery may have failed - dried from cracked cell or drained by internal short in a cell - or old battery and can't supply enough charge to move the Starter Solenoid to make the starter turn the engine over. Inspect the battery and it's wiring - the system is 2007, this is 2022 - 15 years of life - not bad - but hate to see why the engines not turning over...

Low oil level and long park - might lead to a seized motor. Even if the engine was running - coking of the remaining oil on the cylinder walls after shutting off can cause drying (varnishing) of oil and it will seize an engine and keep it from turning over until something can get into the cylinder head thru the spark plug hole, intake or exhaust to lubricate the top piston rings to free them and allow the crank to turn.

IF the TEMP gauge is all the way over Full segments - then the sensor is either open due to failed wire or the connector has popped off.

When it sits - what conditions was it put in? Flood? Rain? High Heat and Humidity?

Was the Coolant level checked?

Any evidence of Tampering?

When you opened the hood, did you find any damage to the wiring?

IN some cases, the connectors simply come loose, but why? (Age? - Corrosion comes to mind)

 

[Chrissyw]

That’s a pic of the dash display
Nothing evident re wiring and connections to the sensors.
battery is new (2 months old ). I cleaned the terminals and checked earth all appears ok.
I think I will try a new temperature sensor.
I read that there is an outside temperature sensor and engine temperature sensor. I take it that it would have to be the engine one that could be faulty. Coolant level is perfect and no leaks apparent.

 

[Chrissyw]

A few pics of test sweep

 

[Handy Andy]

Thanks for using that Test Mode - it certainly shows that the engine temp sensor has either failed or the connector is not seating well enough into it.

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Place a tester - set it to 20K (or 10K setting) and see if an ohmic reading shows up - check it to the case (threaded portion of the body - if it uses the style) make sure it is not shorting out.

IT also may be a diode (PTC) - so it might need to set the DVM to Diode Check and see if the diode is open or shorted - for you should have a reading of something only one way - if none or shows a dead short either way - well, you have an answer.

 

[Handy Andy]

I also had another thought...

There are several "sensors" Motorcraft supplies that if that Fiesta isn't "targeted" right, read this as Right Model and Year - but, Wrong Trim Line or Engine you can get a sensor that is designed to "ground a relay" upon a specific condition - in this case, the overheating condition - the sensor "grounds" or shorts itself to ground which then the expected wiring to the Relay then turns on and the Fan it controls cools down the system.

Doesn't do the job if the system just needs to see where the coolant temp is so the Low-speed fan can come on and save more resources to use when the Turbo or outside Air temp is cool enough that the system can hold a given condition for a longer time improving its efficiency - a simple on-off versus the variable for calculations and outside to engine temp to help with cooling and turbo operations, is what I'm getting at.

There are sensors that provide a value for the Body Control Module or the PCM - which let the "watchdog" see the temperatures at any given moment and is able to control the cooling fan or even AC unit to "cut out" during moments of acceleration or engage during specific moments of drivetime that maximize the cooling systems effectiveness like (the Cold Start) mornings - AC on - just no FAN blowing cold air - or use the FAN but Not the AC to recover cooling once a long term idle condition is relieved. It's things like these that Smart programming helps - improving the effectiveness of the heat exchange trying to take place.

So, the wiring might be fine, just the sensor is not the right one - might want to ask the service personnel to research this.

The reason this comes up, is because the Eco-boost line of engines had shutters for their quick warm up heating and cooling effectiveness, but the standard - Normally Aspirated motors did not have such shutters unless the trim line specified it.

Your dashboard being what it has, reminded me of it.