E09 error code
ACV Prestige MkIII E09 error code – Gas-valve relay error
What does ACV Prestige MkIII 18/32 condensing boiler E09 mean?
ACV documents E09 for the Prestige Solo 18/32 MkIII and Prestige Excellence 18/32 MkIII range as: Gas-valve relay error.
The code identifies the condition detected by the product; it does not always identify the failed component on its own. Confirm the full code and exact model before ordering parts or attempting a reset.
The ACV Prestige MkIII 18/32 condensing boiler E09 error code indicates aCV documents E09 for the Prestige Solo 18/32 MkIII and Prestige Excellence 18/32 MkIII range as: Gas-valve relay error. This guide explains what the code means, the symptoms and likely causes, the checks that are safe to make, and when to stop and arrange an authorised repair.
Symptoms you may notice
The ESYS display shows E09. The boiler may lock out, interrupt burner operation, stop firing, restrict heating or hot-water operation, or remain in a protective blocking state.
Common causes
The official ACV ESYS table associates E09 with gas-valve relay error. The installed model and its water flow, pressure, sensor, fan, ignition, gas, wiring or controller condition must be checked before any part is replaced.
Before you start troubleshooting
Use the display, rating label or product menu to confirm the exact model. Similar-looking codes can have different meanings across product generations and regions.
- Record the complete code before switching the equipment off.
- Check only user-accessible controls, filters and external connections described in the manual.
- Do not open gas, refrigerant, combustion or electrical compartments.
Troubleshooting steps
Record E09 and the exact Prestige MkIII model. Do not remove the casing. Internal gas, combustion, electrical, fan, sensor and hydraulic tests require a suitably qualified heating engineer.
Can you fix this error code yourself?
The safest next step depends on the exact model and the cause behind the code. External checks may help, but a returning fault needs professional diagnosis.
A successful reset is not proof that the underlying issue is fixed. If E09 reappears, note when it happens and give that information to the service engineer.
Reset instructions
Correct the underlying condition first. Use the boiler RESET only when the official instructions permit it. If E09 returns after a permitted reset, stop resetting and arrange qualified diagnosis.
Applicable products and models
Prestige MkIII 18/32 condensing boilerPrestige Solo 18 MkIII; Prestige Solo 32 MkIII; Prestige Excellence 18 MkIII; Prestige Excellence 32 MkIII03/2011 manual 664Y4200 revision HWhen to contact a professional
Contact ACV support or a suitably qualified heating engineer when E09 persists, returns after a reset, affects safe combustion or circulation, or requires internal measurement, adjustment or replacement.
Frequently asked questions
What does ACV Prestige MkIII 18/32 condensing boiler E09 mean?
ACV documents E09 for the Prestige Solo 18/32 MkIII and Prestige Excellence 18/32 MkIII range as: Gas-valve relay error.
Can I fix ACV Prestige MkIII 18/32 condensing boiler E09 myself?
Some external checks may be suitable for the user, but the result depends on the exact model and cause. Use the official manual and arrange service if the code returns.
Should I reset the product after code E09?
Correct the underlying condition first. Use the boiler RESET only when the official instructions permit it. If E09 returns after a permitted reset, stop resetting and arrange qualified diagnosis.
When should I arrange a repair?
Contact ACV support or a suitably qualified heating engineer when E09 persists, returns after a reset, affects safe combustion or circulation, or requires internal measurement, adjustment or replacement.