Handy tips for fault finding
Here at Vaillant, we’ve always made it simple and easy to know the coding behind our fault codes
Monday 15th July 2024
From taking part in one of our practical training courses in our centres of excellence, dialling into the on-demand learning with The Vaillant Academy, or simply installing and servicing Vaillant products yourself, you may have come across F codes already.
By using F and S codes, we’ve standardised some of the faults you may experience on the Vaillant product range. These codes indicate what issue may have occurred with your customer's boiler or heat pump, making it even easier to detect and fix your customer's heating.
Here are five hints and tips for the ecoTEC plus domestic range of boilers:
Please note that this is guidance for our ecoTEC plus range of boilers, please contact our installer technical helpline on 0330 100 3481 for further support.
F61
What does it mean?
There could be a fault with the gas valve, gas valve lead or a PCB fault.
What can you do?
First, we recommend that you check the resistance is correct of the gas valve and that the harness has continuity. If this is correct, then the PCB may need to be replaced.
F62
What does it mean?
There could be a fault with either the gas valve or PCB.
What can you do?
First, you should carry out a local tightness test on the gas valve. If it isn’t letting by then the PCB may need to be replaced.
F27
What does it mean?
There could be a flame detection error or fault with the PCB.
What can you do?
If there is a flame in the burner when the gas valve is shut off, carry out a tightness test on the gas valve.
Alternatively, if the gas valve is letting by then we recommend that you change the gas valve. If F27 still appears at the wrong time during the boiler lighting sequence, then the PCB or electrode may need replacing.
F75
What does it mean?
There could be an issue with the expansion vessel, pump or pressure sensor.
What can you do?
We suggest that you check the pressure sensor and also ensure that the pump is spinning. If this isn’t happening, please check the 230 VAC supply from the PCB. We would suggest draining the boiler down to see if it reads 0.0 to test the pressure sensor. If it reads anything else, we recommend this be replaced.
The next step is to check the expansion vessel is charged between 0.75 and 0.9 bar. If it is, look for a blockage between the pump and the pressure sensor and canoe filter or change the pump. If the appliance was manufactured before 2009, you can also check the rubber hose.
F70
What does it mean?
The replacement of the user interface PCB may not have been set up correctly or there is an issue with the Device Specific Number (DSN) code.
What can you do?
Check the DSN code in D.93 on the installer menu. If the PCB has been recently replaced, make sure the coding resistor (jumper) has been transferred from the old PCB to the new one.
Please note: these fault codes are for the domestic range of ecoTEC boilers manufactured from 2015 and are intended as a guide. For further advice, please call our technical team on 0344 693 3133 who will be happy to help.