Ford Fiesta: Coolant temp guage hits max, without any signs from engine

Took the vehicle to FASS and it's been two days and they still can't figure out what's wrong.

BHPian RiGOD recently shared this with other enthusiasts.

Been happy with my 9 year old Fiesta Diesel it has hardly given me any headache till date.

So one fine morning while driving to office, I noticed that the temperature gauge gradually making its way to maximum. But to my surprise, the engine was running smooth and there were no signs of trouble. By the time I parked the vehicle, the temperature gauge hit 120 degrees and the radiator fan kept running for a while after the engine stopped.

Took the vehicle to FASS and it's been two days and they still can't figure out what's wrong. They checked the coolant temperature sensor, thermostat, the associated wirings and socket. Everything seems to be fine. Still, after driving around 6kms, the temperature gauge hits maximum and the car shows no signs of trouble. Could someone help me out here?

Here's what BHPian dhanushs had to say on the matter:

It's very unlikely that its a temperature guage malfunction. Also, a risky proposition to think like that. So, please dont continue running the vehicle like this, and figure out the root cause. It can be but not limited to Water Pump, Coolant Leak, Gasket failure.

Here's what BHPian GForceEnjoyer had to say on the matter:

I think you might have a genuine overheating problem, because I doubt that a malfunctioning temperature gauge would do this. If it is indeed a gauge malfunction, the exact coolant temperature reading on the diagnostic menu in the MID is likely to be different to what the gauge shows. (To access the menu, keep the odometer reset button pressed for a few seconds after turning the key to position IDoes the gauge take a normal amount of time to reach operating temperature and then just keep climbing? If so, that would probably point to a problem with the cooling system. It could be a simple coolant leak, or something wrong with the thermostat/water pump.

It could be that the thermostat is not opening properly (it is a valve that's supposed to slowly open to let coolant flow to the radiator and back once the engine begins to warm up).

This is all I can say with my layman's knowledge of cooling systems, but if your service centre is unable to find out anything at all, it might be time to reach out to a different workshop.. One of the displays will show you the exact coolant temperature

Here's what BHPian tsk1979 had to say on the matter:

Two things

1. How do you know the coolant level is good. Did you open the radiator when cold?

2. When it goes high, go outside and look at the fan, see if fan is on.

If these two things are not the problem, it could be a water pump failure which is intermittent, or thermostat. Thermostats can go bad often.

Do you lose air conditioning when this happens?

Here's what BHPian asit.kulkarni93 had to say on the matter:

Ford diesels are notorious with fan motor related issues. But in this case, Before you check the electricals please get the radiator cleaned followed by replacement of the thermostat. Please check all the coolant hoses for minor leakages. Then you can check the fan motor resistor and sockets. The ford dealer on their scanner excute actuation tests for the fan. Lastly, you will have to check the Meter cluster too.

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