Technical Service Bulletin

Issue:  Burner is locked out with fault code F6

Applies to:  Vitocrossal 300, CU3A Series (all models)

Vitocrossal 300, CU3A

Important Disclaimer

The information in this bulletin is intended exclusively for licensed heating contractors, and is NOT intended for the end user. This material is NOT intended to take the place of the information contained in the manuals shipped with the product.

Use of this information by unqualified personnel may result in property damage, personal injury or death.

End users are asked to contact a qualified contractor for all installation and service work. If you need assistance finding a contractor in your area, contact your Viessmann Sales Representative, or use our Contractor Locator.

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Symptoms:

The burner is locked out, and fault code "F6" is displayed on the boiler control.


Cause:

Faulty boiler water temperature sensor.


Resolution:

Test and replace the boiler water temperature sensor according to the Service Instructions for Vitocrossal 300, CU3A.


Notes:

The F6 fault code indicates that the temperature values of the dual-element boiler water temperature sensor vary too widely from each other.

This fault code does not appear in the Service Instructions as of this date; updates will be included in the next edition.

Viessmann Technical Services 

Bulletin ID:     TSB-010

Date issued:   Feb 1, 2017

Updated on:   Nov 24, 2017

Revision #:      02

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