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Vaillant Boiler F63 Fault Code

The Vaillant fault code F63 - Circuit board problems Q & A, this is normal related to an electrical issue and if you require an engineer for an emergency boiler repair, feel free to use our service.


The Vaillant Boiler Fault Code F63 Error Common Q&A

Vaillant Boiler F63 Fault Code

Vaillant Boiler F63 Fault Code Error
  • What does the F63 fault code mean on a Vaillant boiler?
  • What can cause the PCB to develop problems, and the F63 fault code to be displayed?
  • Is a boiler with a F63 fault code dangerous?
  • Will resetting the boiler help to fix the F63 error?
  • Besides the fault code, what else signals that the PCB is to blame?
  • If parts in the PCB are worn can they be replaced?
  • What about loose connections, can these be fixed easily and clear the F63 fault code?
  • Why would my boiler smell like it’s burning?
  • How should the engineer setup the PCB, and how can incorrect setup cause a F63 fault?
  • The engineer suggests replacing the PCB to fix the F63, how much should this cost?
  • Should I replace the PCB, or the entire boiler?

What does the F63 fault code mean on a Vaillant boiler

If you have a F63 fault code displayed on your Vaillant boiler, there is a problem with the circuit board (PCB).

The PCB is what communicates with all electronic components.

It tells them when to switch on (such as the pump, to start circulating water) and when to switch off (such as the gas valve, when no further fuel is needed).

What can cause the PCB to develop problems, and the F63 fault code to be displayed

Without a diagnostic, it’s hard to pinpoint the exact issue.

However, common problems with PCB units include:

  • Old age; general wear and tear
  • Connections to and from the PCB have worked loose, or have been damaged
  • The PCB has not been setup correctly by a service engineer after a service, new boiler, or new PCB installation

Is a boiler with a F63 fault code dangerous

Generally, a fault code of this kind isn’t dangerous.

The main faults that cause danger are gas related, which isn’t the case here.

If you do smell gas, turn it off, and call and engineer straight away.

Will resetting the boiler help to fix the F63 error

A reset is designed to be used after a problem has been fixed.

If you are resetting a boiler and the problem hasn’t been fixed, it’s unlikely the boiler will work for long.

As soon as it recognises the fault still exists, it will display the F63 fault code again, and lockout.

Besides the fault code, what else signals that the PCB is to blame

Without a fault code, PCB issues are extremely difficult to diagnose.

However, you might have noticed many odd occurrences from your boiler recently.

A boiler will only work, when the PCB is working.

But, if it’s slowly failing, or has loose connections, the communication between the PCB and other parts in the boiler could be intermittent.

Or, it could be sending the wrong signals.

This could lead to issues such as:

  • Cycling on and off sporadically, even when the thermostat is set to “off”
  • Display panel flickering on and off, as if it’s losing electricity/connection
  • Burning smells coming from the boiler, that have worsened over time
  • Boiler won’t fire up, although everything seems normal and you can hear the fan working (a sign that the PCBs communication with the air pressure switch is not correct, and it’s telling the boiler not to ignite)

    • The list goes on. Effectively, anything that appears random could easily be linked to a problem with the PCB.

If parts in the PCB are worn can they be replaced

When the circuit board has failed simply due to old age, there’s little that can be done to restore it, if you’re looking to be cost effective that is.

The time spent on labour to fix wiring and soldered joints, will end up costing more than simply having the PCB unit replaced completely.

Obviously, this is a much better option anyway. Repairing an old electrical component will prolong its life, but it won’t last as long as a brand-new unit.

What about loose connections, can these be fixed easily and clear the F63 fault code

If you’re lucky enough to have loose connections (and, that’s the only issue), it’s good news.

It’s usually obvious which connections are loose. If not, the loose/weak connections can be found using a multi-meter. And, loose connections won’t lead to you have to have the whole circuit board replaced.

However, damaged connections are a different story.

Like old circuit boards, fixing damaged wiring (depending on the extent of the damage) tends to take too long, and is rarely worthwhile.

Why would my boiler smell like it’s burning

There are multiple parts in your boiler that can produce a burning smell:

  • A stuck pump, whereby the shaft is stuck
  • A seized fan, whereby the motor is overheating

But, when a F63 fault code is displayed, there’s a small chance that water has made its way into the PCB, and some of the small connections have burnt out.

Burnt connections are easily found via visual checks. If burnt connections are the problem, the PCB will need to be replaced.

How should the engineer setup the PCB, and how can incorrect setup cause a F63 fault

When a service engineer installs a new boiler, or new PCB, the circuit board needs to be configured.

Generally, this is a simple case of entering a product code.

If the product code isn’t recognised, the PCB will act as if it’s not connected with the boiler, and its components.

Therefore, the boiler won’t work, and it will display the F63 fault code.

This is a very rare.

When a new PCB is fitted, it needs to be tested, and the service engineer should have seen this fault.

More importantly, if this relates to a new boiler installation, there are various legal checks that need to be done before signing a boiler off.

If the boiler hasn’t been operational (quite obviously not, since the PCB was never connected), there’s no way that these checks have been carried out.

Although it’s unlikely a new boiler is going to be dangerous, these safety checks are there for a reason; for that 1/1000 unlikely case where it is dangerous.

The engineer suggests replacing the PCB to fix the F63, how much should this cost

A PCB swap should cost in the region of £325-£425.

This depends on a few things such as:

  • The time taken to fault find (and therefore, additional labour time)
  • The cost of the PCB (different Vaillant boiler’s PCBs, are different prices)
  • Where you live (labour rates vary throughout the UK)

Should I replace the PCB, or the entire boiler

Once we’re talking about spending £400+ on boiler repairs, a replacement should be considered.

Whether you choose to go for a replacement or not will depend on a few things:

  • Does the boiler have any warranty left?
  • Are expensive parts like the burner and heat exchanger in good condition?

If the answer to these questions is no, it might be time to consider a replacement boiler, rather than investing cash in a boiler that has proved it’s on its last legs.

Other Vaillant Fault Codes And Error

If your looking for the list of error codes relating to the Vaillant boiler then please read the article Vaillant Boiler Fault Codes And Cures