F.083
When the burner starts, no temperature increase is registered at the flow or return temperature sensor or the temperature increase here is too slow.
Vaillant ecoTEC Plus Combi
Possible cause
System pressure too low
Measure
Check the system pressure.
Possible cause
Flow temperature sensor: No contact
Measure
Check whether the flow temperature sensor is lying against the flow pipe correctly.
Possible cause
Fault in the electrical connection for the flow temperature sensor
Measure
Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections.
Possible cause
Return temperature sensor: No contact
Measure
Check whether the return temperature sensor is lying against the return pipe correctly.
Possible cause
Fault in the electrical connection for the return temperature sensor
Measure
Check and, if required, replace the wiring harness between the PCB and sensor, including all plug connections.
Possible cause
Insufficient/no water in the product.
Measure
1. Fill the heating installation.
2. Check the product and the system for leakages.