Low Service
D.98 on Vaillant ecoTEC

This is a prompt or status message indicating that the boiler requires professional maintenance or has reached a specific service interval that needs an engineer's attention.

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.

Technical description

Telephone a heating engineer

What causes this fault?

This message is triggered by an internal timer or a specific number of burner operating hours set by a previous engineer. It physically indicates that the boiler has reached its scheduled maintenance interval and requires a safety inspection rather than being a sign of a mechanical breakdown. The status is designed to ensure the appliance continues to run efficiently and safely through preemptive servicing.

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 →

Related fault codes

Related guides you might find useful