thanks tony, i have got more info on my jaguar 23 combi boiler, first thing is, i have a code, its 02101518133 and theres another one 24ktvj15...
if i cut the power to the boiler, and turn it back on, it fires up as normal until it reaches desired temperature, 80 degrees for example, but instead of comming back on when temperature has dropped (to maintain the desired temperature) it stays off, and you can see the numbers on the PCB board dropping until they reach about 20-25 degrees (room temperature). this indicates to me that the thermostat is working because it is showing me the correct temperature, but its as if the boiler is not responding to it. Could this be a problem with the PCB board?