Vaillant Printed Circuit Board (PCB)

Common Vaillant fault codes indicating a potential Printed Circuit Board (PCB) issue include F61, F62, F63, F64, F65, F67, and F70. The F61 and F62 are the most frequent, suggesting a faulty PCB or, less commonly, a problem with the gas valve. The F70 code specifically appears after a PCB replacement and indicates the need to correctly configure the new board's Device Specific Number (DSN). You should always contact a qualified Gas Safe registered engineer to diagnose and repair these issues, as attempting DIY repairs can be dangerous. 

Fault Codes Indicating a Possible PCB Issue 

• F61/F62:

• These are the most common codes associated with a faulty PCB, though F62 can also point to a defective gas valve. 

• F63/F64/F65/F67:

• These codes generally indicate an electrical fault on the PCB. 

• F70:

• This code appears on older EcoTec models (pre-2012) and signals that the Device Specific Number (DSN) of the new PCB needs to be correctly set after a replacement. 

Why These Codes Point to a PCB Fault

• F61 & F62:

• These indicate issues with the gas flow or valve shutdown. While a gas valve can be the culprit, a failing PCB is a more common cause for these error codes on older boilers. 

• F63, F64, F65, F67:

• These errors are direct indicators of electrical problems within the PCB, possibly due to age or component failure. 

• F70:

• When a new PCB is installed, the boiler needs to "learn" its specific settings, and this code means the DSN hasn't been correctly entered or adjusted. 

What to Do

• Reset the Boiler: Try resetting the boiler by locating the reset button (a flame symbol with a cross through it). The fault may briefly clear, providing time to arrange a repair.

• Call a Gas Safe Engineer: Because the underlying issue can be dangerous and involves gas, you must call a Gas Safe registered engineer to diagnose the problem properly.

• PCBs & Gas Valves: A Gas Safe engineer will test the gas valve and the PCB to determine which component is at fault.

• Configure New PCB (if F70): If the F70 code is present, the engineer will need to enter the correct DSN into the new PCB to pair it with your boiler.