Low
d.34 on Vaillant ecoTEC Plus 615

This code is simply showing you the current speed of your boiler's internal cooling fan and is not a warning of a fault.

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

Value for the fan speed: Current value in rpm. Fan speed=Display value x 100

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Plus 615 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

A cover plan would handle faults like d.34: 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.

All 96 fault codes on the ecoTEC Plus 615

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

cond.10d.11d.13d.17d.18d.19d.20d.22d.23d.25d.27d.28d.33d.35d.36d.40d.41d.47d.50d.51d.58d.60d.61d.64d.65d.67d.68d.69d.70F.0F.1F.10F.11F.13F.20F.22F.23F.24F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.70F.71F.72F.75F.76F.77F.78F22F70P.0P.1P.2P.3P.4P.5P.6S.0S.1S.2S.3S.4S.5S.6S.7S.8S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.31S.32S.34S.36S.41S.42S.53S.54S.96S.98

Related guides you might find useful

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

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 →