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Vaillant F00 Fault Code

This page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. The following information, will take you through the fault finding sequence or steps, for rectifying a Vaillant Ecotec boiler with this fault code. Suggested solutions will be detailed further down the page.

F.00 Meaning

This fault according to Vaillant Instructions and Servicing manual is a Heating Flow Temperature Sensor interruption or Heating Flow NTC Thermistor fault.

Cause of F00

The cause of this fault is that either the

  • Heating Flow NTC Thermistor has become disconnected Or Has Gone Open Circuit (Should Read 12Kohms @ 20C), or
  • Wiring Harness Fault Or Connection Error Between The Heating Flow NTC Thermistor And The Main PCB

Solutions to repair this fault

Test the NTC sensor, test the connection between the NTC sensor and the PCB ie the wiring harness.  Unplug and replug as necessary. Replace the NTC if necessary. Replace the harness if necessary.

Vaillant NTC Sensor

Vaillant Flow / Return NTC 193592

Vaillant PCB X20 Connector
Vaillant PCB X20 Connector
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