A 04 Low

Vokera A 04 Fault Code

Also written as A04 — same fault.

The Vokera A 04 fault code means: your boiler is currently performing a brief automatic system check to ensure everything is initialized correctly before starting up.. It appears on 2 Vokera models in our database.

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: System loading
Typical repair cost £90-150 (including labour)

DIY fix possible

Check your boiler's pressure gauge and ensure it is between 1 and 1.5 barIf the pressure is low, use the filling loop to top up the system until it reaches the green zoneOnce the pressure is correct, turn the boiler off and back on again to reset the system

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like A 04: 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.

Vokera models that show the A 04 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Vokera A 04 fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026