Worcester Bosch Fault Code FA

This page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. The following table will take you through the fault finding sequence for rectifying a Worcester Bosch boiler with this fault code

FA and RESET button and fault indicator LED are flashing. After appliance switches off flame is detected

StepCheck Action
1.Is the condensate trap blocked?yes:▶ Switch OFF the appliance.
▶ Clean out condensate trap discharge pipe.
▶ Switch ON the appliance.
▶ Press the reset button for 3 seconds and release it. After releasing
the appliance re-starts. FA? go to step 2
no:go to step 2
2.Electrode assembly defective?
▶ Switch OFF the appliance.
▶ Remove electrode assembly.
Electrode assembly burnt out?
yes:▶ Replace electrode assembly.
▶ Switch ON the appliance.
▶ Press the reset button for 3 seconds and release it. After releasing
the appliance re-starts. FA? go to step 3
no:go to step 3
3.Problem with flue?
▶ Check CO2 level in combustion air in the flue
(with outer casing fitted). Is CO2 level above 0.2%?
yes:There are flue gases in the combustion air.
▶ Check flue, clean if necessary.
▶ Press the reset button for 3 seconds and release it. After releasing
the appliance re-starts. FA? go to step 4
no:go to step 4
4.Is the gas valve damaged?yes:▶ Switch OFF the appliance.
▶ Disconnect the boiler power connection.
▶ Turn off gas valve.
▶ Change the gas valve.
▶ Open the gas valve.
▶ Reconnect the appliance power connection.
▶ Switch ON the appliance.
▶ Check appliance for leaks.
▶ Press the reset button for 3 seconds and release it. After releasing
the appliance re-starts. FA? go to step 5
no:go to step 5
5▶ Switch OFF the appliance.
▶ Disconnect the boiler power connection.
▶ Check if the 20-pin connector lead assembly
is damaged.
▶ Change the connector lead assembly.
▶ Reconnect the appliance power connection.
▶ Switch ON the appliance.
▶ Press the reset button for 3 seconds and release it. After releasing
the appliance re-starts. FA? go to step 6
6The PCB is damaged.▶ Make a note of the altered service settings.
▶ Switch OFF the appliance.
▶ Disconnect the boiler power connection.
▶ Change PCB control board.
▶ Reconnect the appliance power connection.
▶ Switch ON the appliance.
▶ Restore service settings previously noted down.

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