F.081
Cylinder charging has failed.
Vaillant ecoTEC Plus Combi
Possible cause
Interruption in the wiring harness
Measure
Check the wiring harness to the internal cylinder.
Possible cause
Secondary heat exchanger clogged/blocked
Measure
Check the secondary heat exchanger for dirt.
Possible cause
Pump non-return valve blocked
Measure
Check that the non-return valve for the pump in the internal cylinder is working correctly.
Possible cause
Plug on domestic hot water connection temperature sensor loose/not plugged in
Measure
Check the plug and the plug connection for the domestic hot water connection temperature sensor.
Possible cause
Domestic hot water connection temperature sensor installed incorrectly
Measure
Check whether the temperature sensor on the domestic hot water connection is correctly installed on the pipe.
Possible cause
Pump blocked
Measure
Check that the pump in the internal cylinder is working correctly.
Possible cause
The pump is defective.
Measure
Replace the pump in the internal cylinder.
Possible cause
3-port diverter valve defective or blocked
Measure
Check and, if required, replace the 3-port diverter valve.
Possible cause
Impeller sensor in the shift-load cylinder is defective
Measure
Check and, if required, replace the impeller sensor in the shift-load cylinder.