Hello

I have completely drained the cooling system to replace the coolant in my 1.4 MPI. To refill my Haynes manual says to remove the temperature sensor from the cylinder head to allow air to escape. I pulled out the clip and then lifted out the sensor which came out by pulling. I then filled the system until coolant was seen in the sensor hole. I then the replaced the sensor but noticed coolant leaking from it. On inspection noticed that the sensor was able to move up and down with the clip in position. I cannot see how to make this hold firm especially once the system is under pressure.

Many thanks

Nick

You probably need a new o-ring.

Many thanks, Pete

Yes, that is what it is. Obvious really! Duh!! I have never done this procedure before and what flummoxed me was there was nothing present between the clip and the sensor body not even a sign of debris. No wonder the clip came out with my finger! I can only conclude that the O ring has completely disintegrated and perhaps I wasn't long from losing the coolant should the sensor come loose.

I have to confess that 99.9% of my maintenance experience is on classic cars before O rings became commonplace. An Fabia Mk1 is a modern car to me. This is my second Fabia and as both have been very reliable I have done little to them, just oil changes, brake pads, etc.

Thanks, again!