F.47
FAULT CODE
Vaillant
Short Circuit / Low Voltage on Ionisation
High Severity
Engineer Required
The ionisation sensing electrode is detecting a short circuit or the voltage is too low. The boiler cannot confirm a stable flame.
Step-by-Step Fix Guide
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Step 1
A Gas Safe engineer will need to check the ionisation electrode
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Step 2
The electrode may be corroded or cracked and need replacing
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Step 3 Engineer only
Wiring between the electrode and PCB should also be checked
Gas Safe Reminder
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.