Low
97:2 on Viessmann Vitodens 300 WB3A 66kW

Your boiler is having trouble communicating with the outdoor temperature sensor, which helps the system run more efficiently based on the weather.

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

The outside temperature of the sensor connected to the control unit will be utilised internally and transmitted via LON BUS to any connected Vitotronic 050.

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 300 Wb3a 49 66kw 5862570 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.

What causes this fault?

This fault occurs when the boiler's main control board loses the data connection from the outdoor weather sensor. The most common cause is a loose connection or a break in the wiring between the boiler and the sensor, though it can also be caused by a software glitch in the communication module. Because the boiler can no longer see the outside temperature, it will stop modulating based on the weather and revert to a basic backup setting.

This fault often becomes noticeable during the autumn or spring when fluctuating outdoor temperatures cause the expansion and contraction of the sensor's delicate electrical components.

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 →

Avoid the next call-out bill

A cover plan would handle faults like 97:2: 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

All 90 fault codes on the Vitodens 300 WB3A 66kW

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

Related guides you might find useful