: If the error persists, a gas-safe engineer should measure the voltage to the fan and test the pressure switch's continuity. ⚠️ Safety Warning
: Inspect the communication link and terminal blocks between the EA1 module and the main boiler PCB to make sure the board recognizes the expansion card. Troubleshooting Heat Pumps with Flow Issues viessmann d6 error
: In older units, the internal flow switch mechanism can physically stick due to scaling or particulate buildup. Step-by-Step Troubleshooting and Solutions : If the error persists, a gas-safe engineer