Boiler displays A41; may run at reduced output or shut down

Safety: Electrical work should be performed by a qualified person. Isolate power before opening the electrical compartment.

• 1. Check other appliances: Verify if lights dim or other devices behave abnormally, indicating a general supply issue. If so, contact your electricity provider.
• 2. Inspect power cable and plug: Ensure the Buderus boiler's power cord and plug (or hardwired connection) are secure and undamaged.
• 3. Measure voltage: A technician should measure the mains voltage at the boiler terminals. If outside the specified range (typically 230 V ±10%), the boiler may lock out with A41.
• 4. Internal connections: Check terminal blocks, fuses, and the main power relay on the Buderus control board for signs of overheating or loose screws.
• 5. Power supply module: If mains voltage is stable but A41 persists, the internal power supply or control board may be defective and require replacement.