Boiler intermittently shows code 12, resets may temporarily restore operation

Safety first: Allow the system to cool before topping up pressure. Do not over-pressurize.

User/installer steps:

• Check pressure gauge: On sealed systems, verify that the pressure gauge on the Intergas boiler reads within the recommended range (typically 1.0–1.5 bar cold). If low, top up via the filling loop as per the user manual.
• Bleed radiators: After topping up, bleed radiators and any high points to remove air, then recheck pressure.
• Check for leaks: Inspect visible pipework, radiators, and the boiler for signs of water leakage that could be causing pressure loss.

Technician steps:

• Clean system filter: If a magnetic or mesh filter is installed on the return, isolate and clean it.
• Check pressure sensor: Test the Intergas water pressure sensor or switch for correct operation and replace if faulty.

If pressure drops repeatedly, a hidden leak or expansion vessel fault may exist and should be investigated by a heating professional.