Could a bad coolant (cylinder head ) temp sensor cause hard start from cold ?


Torque Junkie
Ford Focus mk2
Could a bad cylinder head temperature sensor cause hard starting from cold ?

About 5 days ago I came out of the gym and got in my car, it has been parked for about 2 hours, As soon as I put my key in ignition the temp gauge needle went right into red, then bounced to the bottom, I started the engine and the temp gauge shot into red, then bottom, then red, then bottom, as I started driving the gauge continued to hover for a bit and then settled below 90 at a steady reading.

Next day after the car was parked overnight and I got in in and started the engine it started for 1 or 2 seconds and cut out and did this about 5 times before the engine finally stayed running, it idles dodgy for about 15 seconds but then was normal.

After the cold start it runs fine all day and night until the next morning when I start my car.
It is the initial start - up that is the problem.

Could a faulty temp/cylinder head sensor cause this ?

In a word YES, but to save the guess work and possibly throw good money away, get the ECU interrogated by a tech II machine to see what fault codes if any are coming up.
I would have suggested that the water temp sensor may be the culprit or an inlet air temp sensor if your car has one. T9's scan tool test recommendation should hopefully show where the fault lies.

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