Ariston Combi euro boiler SX20 MFFICE 970903039 GC...

Question

I have the above boiler which comes on as normal and the temperature gauge rises anything from 40 - 60, the boiler cuts out all the time and the red warning light comes on and I have to press to re-ignight the boiler. Could this be the therma couples which I understand there are 2 of? For your information, earlier this year I had a new expansion vessel.
Any help would be much appreciated to get it working.
Many thanks
Glynis