Vaillant F54 & F28 fault code help

[billski]

Anyone had any experience with F54 & F28 fault code on a Vaillant Eco tec plus 831?
It locks out but if you leave it for a while, sometimes days, it fires back up. Fiddled about with the wiring harness and it seemed to sort it for a while, but not sure if that was coincidents. I'm guessing it can only be the gas valve or power to it.. board was replaced about a year ago so hoping it's not that.

 

[Burger]

F28 is usually a lack of gas, but can be the condense pipe blocked, an issue with the flue, spark electrodes, spark lead, and a few others. F54 - a new one on me, you sure that she the correct code?

 

[billski]

Yeah it's definitely F54. Says fault with gas supply but I've tested the gas meter and everything checks out.

 

[ShaunCorbs]

Have a look at the status eg where it gets upto

I’ve just fixed one the pressure sensor was blocked (electronic) so it wasn’t sensing the pump was running nice easy one for a change

 

[EvilDrPorkChop]

Does F.54 say 'defective Gas Valve' in the manual or is that f.63/f/64?

 

[billski]

[F.54 Gas pressure fault (in combination with F.28/F.29) No or too little gas supply pressure, gas valve closed
That's what the manual says.