S.12
FAULT CODE
Vaillant
Status: Pump Over-Run After Heating
Medium Severity
DIY Check Possible
The boiler has finished a heating cycle and the pump is running to dissipate residual heat. This is normal behaviour.
Step-by-Step Fix Guide
-
Step 1
This is a normal status — the pump is cooling the heat exchanger after the burner has shut off
-
Step 2
No action is required
-
Step 3
The pump will stop automatically after the over-run period
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.