BoilerFaultCodesVokera Test 4 Fault Code
Also written as TEST4 — same fault.
The Vokera Test 4 fault code means: your boiler is failing to light the burner, meaning it cannot produce heating or hot water safely.. It appears on 1 Vokera model in our database.
Technical description: Ignition fault
What causes the Vokera Test 4 fault?
This fault occurs when the boiler's control system attempts to start a flame but fails to detect one after several attempts. The most common reasons are a lack of gas reaching the burner, a worn-out spark plug that can no longer create a flame, or an internal sensor failing to recognise that the boiler has successfully lit.
This fault is more common during the first cold snap of winter, when increased demand can highlight underlying issues with the gas valve or electrodes that went unnoticed during the summer.
DIY fix possible
Check if other gas appliances, like a hob, are working to ensure gas is reaching your home.Verify that your gas meter has credit if you use a pre-payment system.Try resetting the boiler by turning the control knob to the 'Reset' position and holding it for a few seconds.
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Gas Safe Register →Vokera models that show the Test 4 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera Test 4 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 27 April 2026