sime friendly format 80e - Red light?

My boiler was working fine but the pressure had dropped and there was little warm water making it upstairs. So I followed the instructions to increase the pressure back to 1.5
Since then every time it turns over the flame fails to ignite and a red light comes on next to the dial.
I have had the boiler serviced approx 18months ago and a part was also replaced. The plumber had noted it was in very good condition so I assume this is something I have caused.