Radiator fans won't stop! C5 2.2 HDi

[Millerboy79]

Hello,
My coolant sensor popped out of the thermostat housing the other day for a wander around the top of the gearbox and obviously let all the coolant out with it! I got the usual "coolant temp too high" warning and the big red stop! And the rad fans kicked in, and are still running, all the time, ignition off still going, no coolant still going, battery off for 16 hours fans still going! How the hell do I make them stop properly as I fear my technique of pulling the plug out of them is simply a temporary solution!
Cheers Todd

[CitroJim]

Todd, they're running because you pulled the wires on the sensor! This is a fail-safe in case of failure of the sensor to ensure things are kept cool by running the fans constantly. Your sensor has failed...

In some other PSA cars, pulling the sensor wires is a good diagnostic test for the fans...

[Millerboy79]

Well that's annoying as it was a brand new sensor that I fitted last weekend, hence it's wandering around on friday, the housing broke (I broke the housing) while changing it, so I siliconed it in, that blew out and it is now chemical metalled in! I'll check the wiring as the plug is slightly damaged.

[Millerboy79]

On a further point would that same fail safe make the fans run constantly, even just over an hour after the ignition has been turned off? Or is there a relay that may be stuck?

[Millerboy79]

Left the fans unplugged for nearly a week, plugged them in today and they have not spun once! Aren't citroens unique!!!!