Vaillant ecoTEC Plus 831 F.27 fault service and repair

vaillant ecoTEC f.27 fault service and repair

I was recently asked to have look at an F.27 fault code on a Vaillant ecoTEC Plus 831 Combi boiler which wasn’t working, in Hillsborough, Sheffield S6. The customer said the boiler would try and fire up and immediately shut down.

The F.27 fault code on the Vaillant ecotec Combi Pro and Plus models and System boilers like the Plus 630, 637 models etc is a fairly common fault on these models of boiler. If your boiler shows this fault code you may be able reset your boiler and it may continue to work for a while then fault again with the same fault code.

If you are having to reset your boiler to get it going due to this fault code then you are running it on borrowed time, and should get it looked at by a professional at your earliest convenience, because it will more than likely stop working entirely at some point in the near future. Sometimes they may continue work for a few days or weeks but always fail eventually and won’t be reset. Your boiler may even show the F.27 with the F.61 or F.62 faults at different times.

If you look up the F.27 fault code in the installation manual it says the following;
Incorrect sensing of flame ▶ Flame detector defective.

Depending on the model the installation manual may even say something like this;
Monitoring electrode reports an incorrect flame ▶ Check: Gas pressure at upper test opening, monitoring elec- trode, PCB, gas solenoid valve.

I don’t think I have ever come across a boiler where the fault was related to a defective flame sensor or ionisation probe. However, I have been asked to go and repair this problem where others have tried and replaced the flame sensor and or other components, charged the customer for their time and parts and have left them with the same problem only for them to have to try and find someone else who can repair their boiler.

A lot of the time this fault is related to the circuit board but if you start guessing and replacing the wrong components it can get expensive very quickly.

Vaillant ecoTEC Plus Combi boiler F.27 fault caused by faulty printed circuit board

Vaillant ecoTEC Plus Combi boiler F.27 fault caused by faulty printed circuit board
This particular boiler did need to have the printed circuit board replaced and I was able to service and repair it in one visit as I carry the parts.

I have been repairing Vaillant ecoTEC boilers with faults such as this for almost ten years now, and almost exclusively as an independent Vaillant engineer for the last six years plus. Needless to say I have a lot of experience with these boilers and this particular problem. I do carry a lot of parts for the Vaillant ecoTEC range of boilers and always try to repair a boiler in one visit if I can.

Richard contact numberemail address

Areas where I can repair your Vaillant ecoTEC Plus Combi boiler

areas that are covered

I cover a large part of South Yorkshire including most of Sheffield, Rotherham and Barnsley. I also cover a small part of Doncaster.


I cover most of Sheffield including central Sheffield, Chapeltown, Ecclesfield, Grenoside, High Green, Oughtibridge, Thurgoland, Wortley, Aston, Aughton, Swallownest, Todwick, Hillsborough and Stannington.


I cover the whole area of Rotherham including central Rotherham, Brinsworth, Catcliffe, Canklow, Masbrough, Treeton, Whiston, Greasbrough, Kimberworth, Thorpe Hesley, Rawmarsh, Wentworth, Bolton-on-Dearne, Goldthorpe, Thurnscoe, Wath-on-Dearne, Mexborough, Swinton, Kilnhurst, Hooton Roberts, Ravenfield, Thrybergh, Bramley, Hellaby, Maltby, Thurcroft, Wickersley and Braithwell.


I cover most of Barnsley including central Barnsley, Birdwell, Stairfoot, Worsborough, Kendray, Ardsley, Athersley, Monk Bretton, Lundwood, Royston, Brierley, Cudworth, Cortonwood, Great Houghton, Shafton, South Hiendley, Brampton, Darfield, Wombwell, Hemingfield, Elsecar, Hoyland, Jump, Barugh Green, Cawthorne, Darton, Dodworth, Gawber, Mapplewell, Pogmoor, Staincross, Wilthorpe, Worsbrough, Thurnscoe and Tankersley.


I cover a small part of Doncaster including central Adwick, Conisborough, Edlington, Warmsworth and Mexborough.