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BoilerCodes
DUIdeal

Ideal DU: diverter valve in mid-position for service

Checked against Ideal's own documentation: Ideal Heating: what does my boiler fault code mean? (page 2). Last reviewed October 2026. How we check

You can usually fix this

Ideal's general fault code guide describes DU as: diverter valve in mid-position for service. Ideal's fix is a simple restart sequence.

What you can safely do

  1. Turn all the knobs on the boiler fully clockwise.
  2. Switch the boiler off, then switch it back on.
  3. Press restart.

Call a Gas Safe engineer if

  • DU stays on the display after this: book a Gas Safe registered engineer.
Find a Gas Safe engineer near you Opens the official Gas Safe Register search.

Applies to Ideal boilers (Ideal's general fault code guide). Codes can differ between models, so check your manual.

What DU means on each Ideal model

From Ideal's own fault tables. Your model name is usually on the front of the boiler or in the user manual.

ModelMeaning
Ideal boilers (Ideal's general fault code guide)Diverter valve in mid-position for service

Common questions about Ideal DU

Can I fix Ideal DU myself?

Only the checks listed above. If they don't clear it, it needs a Gas Safe registered engineer.

Nearby Ideal codes

See all 23 Ideal codes

Sources

Last reviewed October 2026. Spotted something that doesn't match your manual? Email hello@boilercodes.co.uk and we'll check it. How we check