De Dietrich MPX 24 Compact Boiler Error 128: Flue Pressure Fault Troubleshooting

Hi, I have a De Dietrich MPX 24 Compact boiler showing an error code 128, the control panel is flashing with this code. I have googled this code, and it's showing me De Dietrich error code 128 is typically a flue pressure fault, which can be caused by blockages, high winds, or issues with the pressure switch itself. A persistent error may require a technician to inspect the flue, pressure switch, and tubing, though you can sometimes resolve it by checking for obstructions, ensuring the flue isn't exposed to excessive wind, or by resetting the boiler. I have done a reset on the boiler, and this has not helped. I have checked the flue and there is no obstruction. I have tried to reset this myself, and nothing is working. Does anyone have any ideas on what I could do next without having to call a professional? :(

AI: Are there any other symptoms with the boiler, like strange noises, intermittent operation, or any other error codes showing up?
No
AI: Have you had a chance to check the pressure switch tubing for any blockages, kinks, or signs of water inside?
No

Code erreur 128 chaudière De Dietrich MPX MI Slim
Bonsoir, faites un réglage de combustion.
À mon avis, vous êtes en excès d'air au débit gaz minimum de l’électrovanne gaz.
Les valeurs optimales au mini gaz sont 8,5 % CO2 et 9,5 % CO2 au débit maxi gaz.
Pour cela, il vous faut un analyseur de combustion.
(Sous réserve d'avoir les bonnes pressions de gaz naturel, 20 mbar en statique et 17 mbar en dynamique).
Au pire, visser 1/8 de tour la vis du débit mini gaz (offset) sur l'électrovanne gaz.