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Vaillant F26 Fault Code

Welcome to the fault-codes section of this site. The following table or page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. You may be guided through the fault finding sequence or steps, for rectifying your boiler with this fault code. Suggested repair solutions may be provided by a link to a repair page. NB Some fault codes are only applicable to a specific range of boilers only.

Vaillant F26 Fault Code

This fault code is applicable to 2 different models, with different meaning. The one shown here is for the Ecotec range of models. The meaning of it is that there is a fault with the stepper motor that activates the gas valve.

F.26 Fault Code Repair

In order to fix this fault you will need to check from PCB to Gas valve that the electrical connection is not broken.

Image 1: Vaillant X25 Connecor



Image 2: Vaillant Gas valve with stepper motor



Shown above is the Vaillant X25 connector (pointed by the yellow arrow) that connects to the gas stepper motor shown in Image 2. The yellow connector in image 2 is for the stepper motor. So check the connections between the two parts, also checking cable continuity and values if obtainable from Vaillant technical.


Image 3: X25 Connector diagram.


Shown Image 3 is the electrical diagram for the gas valve showing stepper motor connection to the X25 connector.

Where to buy above mentioned parts

See results on Ebay

Part numbers for Gas Valves:

Following is a list of Gas Valve part numbers for a range of Ecotec boilers.

0020148381 Gas Section with Regulator. Used in: Ecotec Plus 612, 615,618,624,630; VU XXX/5-5, VU XXX/5-5 R1, VU XXX/5-5 R2, VU XXX/5-5 R4

Disclaimer: Information on this website is provided for informational purpose therefore we cannot accept liability for subsequent problems. All repair tasks should be carried out by qualified trades people. We may also receive commission payments when you are taken to external websites and complete purchases from third party sellers, once you leave our site, we cannot be held liable for your purchases.