Low
F.14 on Viessmann Vitodens 100-W WB1A

Your boiler is receiving an incorrect signal from the weather sensor outside your home, which may cause your heating system to work inefficiently.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Short circuit, outside temperature sensor

From this model's manual
Verified against the Viessmann Vitodens 100 W Wb1a installation & service manual, page 83.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Locate the external temperature sensor, usually mounted on a north-facing wall.Check that the wiring connection at the sensor has not become loose or corroded by the weather.Inspect the cable for any visible signs of damage, snapping, or short-circuiting.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like F.14: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

F.13View →

Related guides you might find useful

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →