STOP warning indication

[DIY Mechanic Mike]

My Citroen C3 1.6 HDi (2013) car has been parked up in my garage whilst I was away on holiday. On return car started immediately but I needed to get some fuel. Drove about a mile to fuel station and back home again. No problem detected. Car now on drive overnight with outside temperature of -2 degC. Driving to work after about 3 miles car abruptly stopped. I had only the red “STOP” warning displayed on the instrument panel and “Engine fault: stop the vehicle” on the multimedia display. I checked diagnostics menu but no fault shown. I could hear the electric fan going so due to outside temperature and the fan going I suspected coolant system. The handbook also suggested coolant system. After half an hour car engine had cooled down enough for me to get the car home. Checked the antifreeze and all good. Removed top and bottom hose on radiator and flushed water through again this seemed ok. My limited understanding of the coolant system pointed me in the direction of the thermostat, I thought that with the car laid up for a few weeks, maybe the valve is stuck. Also as car is 10 years old I ended up replacing the water pump (including cam belt) as well. Refilled car with 4 litres of antifreeze and bleed water system. But car still has issue. In summary - thermostat which included the temperature sensor and water pump has been changed. One more thing I have noticed is the hoses to the top and bottom of the radiator seem cold, although this could be that the coolant is not getting warm enough to trigger thermostat. One other thought I had was the fuel, but the way the car just stops does not seem to be like a fuel issue.

[DIY Mechanic Mike]

One other thought that just popped into my head, the heaters inside the car work fine, so I guess this means the water pump is pushing hot water around engine, just not around radiator.

[GiveMeABreak]

1) Did you follow the proper bleeding procedure?
2) The vehicle will have an air heater resistor as part of the vehicle heating system, which helps heat the passenger compartment in lower temperatures to aid with demisting, whilst the engine warms up, so this may be the heating you are detecting in the cabin.

A proper diagnostic is really required. Your vehicle's on-board diagnostics will not show 99% of any faults and won't show any fault codes in any case.

Get a proper diagnostic done on it first and them pop any fault codes up here with your VIN.

[DIY Mechanic Mike]

Convinced that the fault was the thermostat, I removed the new thermostat and tested it in a bucket of boiling water. The valve did not open at first, but after fiddling with the mechanism I managed to get it to work OK, reassembled and now car working. I guess there is a reason why OEM parts are more expensive.