Ariston AFA250 - 2nd green light flashing after use?

my machine is only 14 months old and this has just started happening again for the 3rd time. The first two times it was fixed under the 12 month guarantee, but thats now run out and I did not renew. when i asked engineer's opinion on insurance when last fixed in june (when my renewal was due end of month) he said these things do usually break, dont renew!) The engineer said the 2nd light was something to do with the thermostat. Anyone know if I can fix this myself or would I have to get an engineer. Has anyone else had this problem?