Hi there, We have a Vaillant boiler "ecotec plus 837". Yesterday night it wasn't on. The fault code read "F.28 - ignition failure". The manual said to restart the boiler. I did this. The first time the fault came up again very soon. The second time the fault was gone and we had heat all evening. This morning the fault is back - F.28 but this time in combination with "F.54" - which the manual tells me is a fault with the gas supply. I reset the boiler again, and came back to check after 5 minutes. The fault code had now gone back to just F.28. I reset it again and now we have heat. The gas cooker hobs are and have been working fine, and we've had no work done on the pipes, so gas supply seems unlikely to be the issue. Water pressure is fine. Some time during last week we had a power cut. The boiler has been working fine for 4 or 5 days since though. I know from the manual F.28 can be a number of things. If it comes back, is there anything I should try before giving up and calling an engineer? Many thanks.