When this code appears, your boiler will enter a safety lockout state. This means it will stop heating your water and radiators immediately.
Understanding the root cause is the first step to a solution. The D6 error for heat pumps is almost always a water-flow problem. The flow can be blocked or reduced by one of several issues.
Check for blockages in the exhaust system. viessmann d6 error
: Systems designed without an automatic bypass/overflow valve cannot guarantee a minimum flow rate when zone valves shut off.
Because the EA1 module is used to integrate external components, the "real" problem often lies outside the boiler itself: External Pump Failure: When this code appears, your boiler will enter
: Pockets of air trapped in the main distribution lines, inside the secondary heat exchanger, or around the circulating pump mimic a low-flow scenario and trip the sensor.
Did the error occur , or has the boiler been making unusual noises recently? The D6 error for heat pumps is almost
The error reads as a "Flow Switch D6" or "Strömungssensor" fault . This means the internal flow rate has dropped below the minimum threshold required to safely operate the compressor or electric booster heaters.
Trace the two wires connected to the DE1 terminal for visible breaks. Eliminates hardware wire cuts.
Boiler repairs should be done by Gas Safe registered engineers. You can perform the following safety checks, but do not open the boiler casing if you are not qualified. 1. Reset the Boiler Sometimes, the D6 error is a temporary issue. Locate the reset button on your Viessmann control panel. Hold it down for a few seconds.
