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Viessmann Boiler 10 Fault Code

The Viessmann fault code 10 relates to no flame signal and here we have Q & A or require an engineer for an emergency boiler repair.


The Viessmann Boiler Fault Code 10 Error Common Q & A

Just below, we have a list of common questions relating to the 10 fault code on the Viessmann Boiler.

Viessmann boiler error code 10
  • What does it mean if fault code 10 is shown on the display panel of my Viessmann boiler?
  • Why does my boiler lockout?
  • Will resetting my boiler fix the fault?
  • What can cause fault code 10 to show on my Viessmann boiler?
  • The flame sensor isn’t the problem, what else can my boiler engineer check?
  • How can gas pressure affect the boiler’s ability to create a flame?
  • What does the gas valve do, and how can this contribute to fault code 10 being displayed?
  • Can a gas valve be fixed if it’s sticking?
  • How much does it cost to replace a gas valve on a Viessmann boiler?
  • What do the flue and condensate pipe have to do with flame detection?
  • What does my boiler repair company need to check in connection with the burner and jet?
  • My boiler engineer thinks the problem is with the PCB, does this sound right?
  • How much does it cost to fit a new PCB on a Viessmann boiler?

What does it mean if fault code 10 is shown on the display panel of my Viessmann boiler

One of the common Viessmann errors, is when fault code 10 is shown on the display panel. In this instance, the boiler has locked out the burner as there’s no flame signal.

Why does my boiler lockout

All modern boilers have a lockout function.

Your appliance is monitored and controlled by the printed circuit board (PCB). It’s the PCB that gives and receives signals to all important electrical components to ensure that the boiler is working correctly. One of those comes from the flame sensor, ensuring the flame in the burner is present when it should be, and vice-versa.

With the flame signal not being present when it should be, the PCB recognises there is a problem. As this could be a dangerous fuel supply issue, the boiler locks out to ensure that the appliance isn’t posing a threat in your property.

Will resetting my boiler fix the fault

If error code 10 is being displayed on your boiler’s display, you shouldn’t try and fix this on a DIY basis with a reset. The reset function on Viessmann boilers is only designed to be used once the problem has been rectified.

And, working on boilers can be extremely dangerous, especially for those that are untrained. If you are unsure whether your boiler could be dangerous, you’ll need to call an emergency boiler repair company. They’ll have Gas Safe registered engineers that will be able to diagnose the problem. Once the problem is fixed, they’ll be able to reset the boiler to clear the 10 fault code from the display panel.

What can cause fault code 10 to show on my Viessmann boiler

The first thing your boiler engineer will need to check, is the state of the flame sensor. The flame sensor informs the PCB whether the flame is active when it should be. If there’s a problem with the flame sensor, it might be giving the PCB the wrong information. For instance, the flame could be present, but the signal the flame signal is giving the PCB suggests that the flame isn’t active.

So, your boiler engineer will need to test the flame sensor. Using a multi-meter, they’ll want to check not just the flame sensor, but the wiring and connections to and from the main PCB. If there are any breaks in the circuit, either the flame sensor needs to be replaced, or the offending wires/connections need to either be replaced or repaired.

The flame sensor isn’t the problem, what else can my boiler engineer check

After ensuring the flame sensor is operating correctly, your Gas Safe engineer will need to focus on other errors that can affect the boiler’s ability to establish that a flame is present.

This includes a mains input voltage problem, that might mean that electrical parts aren’t receiving the electrical power that they need. They’ll need to check for a poor earth, then check for the likes of reverse polarity.

If that’s not the case, they’ll want to focus their attention on the boiler’s ability to produce a flame, and that’s going to mean checking the:

  • Gas pressure
  • Gas valve
  • Flue and condensate pipe
  • Burner and jet
  • PCB

How can gas pressure affect the boiler’s ability to create a flame

For the burner to receive a steady supply of gas, the gas pressure needs to be correct. Your boiler engineer will need assess all aspects of the gas run to figure out at which point, the gas pressure drops. For instance, they’ll want to check pressure into the meter, out of the meter, and into the boiler.

In the colder months of the years, it’s typical for the meter to be the root cause of a reduction in gas pressure.

Each meter has a small regulator that helps to control the flow of gas. Unfortunately, these regulators are prone to freezing. If your meter is exposed to the elements, it’s a good idea to box it in, and lag the meter. This will protect it from freezing cold conditions.

What does the gas valve do, and how can this contribute to fault code 10 being displayed

The gas valve is an extremely important component in your boiler. Utilising a wiring harness, it’s able to communicate with the PCB. This isn’t just so it can receive signals to open and close when you turn up/down your heating or hot water. It’s also connected, so the PCB can monitor what the gas valve is doing. Most importantly, the PCB needs to see that the gas valve is responding to the commands it’s sending.

One problem that occurs often, are valves that stick. Gas valves are moving mechanical parts. Due to general wear and tear they can get stuck. So, no matter what the signal the PCB is giving the gas valve, it might not be able to operate correctly. This is going to mean in some instances, the gas valve is still open when it should be closed, letting-by gas.

On the flip-side, when it should be open, it’s stuck closed. That’s going to mean that gas isn’t being allowed into the burner and ultimately, a flame can’t be produced.

Can a gas valve be fixed if it’s sticking

Your Gas Safe boiler repair company will need to assess the state of the gas valve, to determine whether it can be fixed. On some occasions, a sticking gas valve can be freed. However, your boiler engineer needs to be confident that the same problem isn’t going to happen again. Otherwise, replacing the gas valve is likely to be the best route forward.

How much does it cost to replace a gas valve on a Viessmann boiler

A gas valve replacement for Viessmann boilers tends to sit in the £250-300 range. The exact price will depend on the model of your boiler. Typically, you should expect the job to take around one day to complete.

What do the flue and condensate pipe have to do with flame detection

There might be a valid reason for a flame not being detected. If your boiler’s flue or condensate pipe are blocked, it wouldn’t be safe for the boiler to fire up.

The flue expels harmful gases from your boiler with the help of the fan. If debris has made its way into the flue, these gases won’t be expelled, and the boiler could be dangerous. So, your Gas Safe engineer will need to inspect the flue, and clear away any debris before resetting your boiler.

The condensate pipe works in a similar way, but instead, takes harmful condensed gases from your boiler. If this is blocked, the boiler is dangerous and will lock out until the problem has been fixed.

Condensate pipe blockages are common in winter. The boiler’s condensate pipe can freeze, enough to cause a blockage. Thawing out the condense pipe will clear the blockage. All that’s left to do then is reset the boiler to clear fault code 10 from the control panel.

What does my boiler repair company need to check in connection with the burner and jet

Assuming there are no blockages and the fuel supply is good, the problem could be with ignition. Your boiler repair company will want to check the burner and jet, to ensure that they are providing a positive environment for ignition.

They’ll start by checking the burner for debris build-up, mainly carbon. If the burner is blocked with carbon, it’s going to need to be cleaned.

But, the more likely cause of the problem here, is the jet. The jet is a small component that allows gas to flow into the burner.

Even the smallest piece of debris can cause a blockage. And, that’s going to mean that gas supply to the burner is intermittent at best. The jet will need to be cleaned, refitted, and the boiler will need to be reset to clear the 10 fault code.

My boiler engineer thinks the problem is with the PCB, does this sound right

With any fault on modern boilers, the PCB needs to be analysed. It’s the PCB that gives and receives signals to all electrical components, to ensure the boiler operates smoothly. So, when the PCB starts acting sporadically, so does the boiler.

As an example, the PCB might not be receiving the signal from the flame sensor to say that the flame is active, even when it is. That’s going to lead to confusion, and the boiler locking out.

Just as they did with the flame sensor, your boiler engineer is going to need to assess the PCB. They’ll test wires and connections, repairing or securing them where necessary. And finally, they’ll test the PCB for power.

If the PCB on your Viessmann boiler isn’t getting power, your boiler isn’t going to work. It’s likely a replacement is going to be needed.

How much does it cost to fit a new PCB on a Viessmann boiler

A PCB replacement could be as much as £500, as it’s one of the most expensive parts to replace.

With such high repair bills, it’s worth having your engineer inspect the overall condition of your boiler. If other expensive components are showing sign of excessive wear, it’s likely a replacement boiler is going to be a more cost-effective solution in the long run, rather than a repair.

Other Viessmann boiler issues

For more boiler issues regarding the Viessmann Boiler then please visit the Ideal Boiler Problems And Cures page.