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Resetting a boiler

Checked against its sources: Updated

How to reset a boiler depends on the model: printed methods run from one brief press to a five-second hold or a quick turn of a knob.123 Use your own manual's method, once.

Covers
Gas boilers in UK homes whose user manuals were read; check your own model
You
Reset once, by the method in your own user manual, if the manual allows it for that fault.
A professional
Any fault that returns, won't clear or shows a symbol your manual says you can't reset.

1 What a reset does

A reset asks the boiler to try again after a safety lockout. It does not repair the cause. Worcester's Greenstar i ErP guide says some codes can't be cleared this way, and an engineer's visit is then needed.1 Ideal's guide says that if a fault is known or suspected, the boiler must not be used until an engineer has corrected it.3

Don't use a reset as a response to a gas smell, a carbon monoxide alarm or a suspected unsafe appliance: see if you smell gas and carbon monoxide. HSE says it is against the law to keep using a gas appliance you suspect is unsafe.12

2 Method by boiler

What each user manual read says about resetting
BoilerPrinted methodPrinted limit
Worcester Greenstar i ErPPress reset "briefly once"1None
Worcester 8000 LifeBoth keys held together, until the fault goes11None
Worcester 2000Off and on again, or both arrows pressed at once13None
Vaillant ecoTEC plus, 2023 issueHold reset for more than 3 seconds43 repetitions
Vaillant ecoTEC plus 2021, ecoTEC pro 2017Fault clearance key for 1 second583 attempts
Baxi 400, 600, 800 Combi 2Hold 5 seconds2None
Baxi Platinum CombiSelector at reset, at least 5 seconds14None; contact if regular
Baxi 600 HeatRESET for at least 5 seconds6Up to 5 in one hour
Main Eco Compact CombiAbout 1 second; over 2 seconds will not reset. A flowchart in the same guide says 5 seconds10None
Glow-worm Energy7Reset for 1 second73 attempts
Glow-worm Ultracom 2 cxiPress reset, wait 5 seconds9None
Viessmann Vitodens 050-WPress the two keys for about 4 seconds15"Not several times in quick succession"
Ideal Logic, Logic+Mode knob to reset, then immediately back35 in 15 minutes triggers its own fault

These are examples, not a full list. The maker entries give more models: Worcester Bosch, Vaillant, Baxi, Main and Potterton, Ideal, Glow-worm, Viessmann.

3 How many tries

Reset once. Where a manual prints a limit, treat it as a ceiling and not a target. Where none is printed, that is not permission to keep going: the Worcester documents read give no number, but send a persisting fault to Worcester or an engineer.111

4 Before and after

  1. Note the code first, as Viessmann's manual asks.15
  2. For a pressure code, deal with the pressure first (repressurising). Vaillant's 2023 manual says F.22 clears by itself when pressure recovers.4
  3. After thawing a condensate pipe, reset as your manual says (frozen condensate pipe).
  4. Stop if the fault returns, and give the engineer the code.

Sources

  1. Greenstar i ErP, 2015/03 issue, document 6 720 806 946, from Worcester Bosch p25, read 3 November 2026.
  2. Baxi quick start guide 7876395-01, covering the 400, 600 and 800 Combi boilers p3, read 3 November 2026.
  3. Logic+ Combi, Ideal, UIN 204979 A07, May 2014, copy on Selco's site, a merchant pp5, 7, 17, read 3 November 2026.
  4. ecoTEC plus ..CS/1-5, Vaillant, 0020308119_03, 28.11.2023 pp6, 14, 20, read 3 November 2026.
  5. ecoTEC plus ..6/5-5, Vaillant, 0020245033_02, 26.05.2021 p14, read 3 November 2026.
  6. 600 Heat, Baxi, 7726861-01, 1/19 pp14, 23, read 3 November 2026.
  7. Energy7 combi, Glow-worm, 0020300878_00, 02.03.2020 p14, read 3 November 2026.
  8. ecoTEC pro, Vaillant, 0020244996_01, 03.08.2017 p12, read 3 November 2026.
  9. Ultracom 2 cxi, Glow-worm, 0020085232_01, 03/10 PDF p15, read 3 November 2026.
  10. Eco Compact Combi 25, 30, Main, 7716571-04 pp14, 16, 21, read 3 November 2026.
  11. Greenstar 8000 Life, Worcester Bosch, 6720883872, 2021/05 p11, read 3 November 2026.
  12. HSE domestic gas FAQ page, the unsafe appliance answer read 3 November 2026.
  13. Worcester 2000, Worcester Bosch, 6 721 814 552, 2019/09 p11, read 3 November 2026.
  14. Platinum Combi, Baxi, 7697821-01, 1/18 pp3, 8, read 3 November 2026.
  15. Vitodens 050-W, Viessmann, 6173895 GB, 05/2026 pp25, 28, read 3 November 2026.