Low
18 on Viessmann Vitodens 200-W B2HB-30

Your boiler has lost the reading from its outside temperature sensor, so it is guessing the weather and still heating your home, though it may not adjust the heat as accurately as it should.

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

Regulates as if the outside temperature were 0 °C. Cause: Lead break, outside temperature sensor

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 200 W B2hb B2kb 5792013 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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

Avoid the next call-out bill

Monthly cover means no unexpected bills when your boiler breaks down.

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

17View →19View →

All 89 fault codes on the Vitodens 200-W B2HB-30

Seeing a different code? Every code this model can display, in one place.

9A9b9C9E9F101920283038505158597071737475768080/EE8181/EE8282/EE838485909192939495969899A3A7A9B0b1b5b7B8bFC1C2C3C4C5CdCFd3d4d5d6d7d8E0E1E2E3E4E5E7E8E9EAEbECEdEEEFF0F1F2F3F8F9FAFbFCFdFEFF

Related guides you might find useful

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 →

Boiler service cost

What a UK service costs and what a proper one includes.

Read →