Viessmann Boiler 0C Fault Code
The Viessmann fault code 0C related to insufficient power supply and incorrect flame signal and here we have Q & A or require an engineer for an emergency boiler repair.
The Viessmann Boiler Fault Code 0C Error Common Q & A
Just below, we have a list of common questions relating to the 0C fault code on the Viessmann Boiler.
- What does the 0C fault code mean on my Viessmann boiler?
- Can the 0C fault be fixed on a DIY basis?
- If I have an insufficient power supply, what should I do?
- If the flame signal is still present after the boiler is switched off, what does this mean?
- How will my emergency boiler repair company know if the flame sensor is faulty?
- What does the gas valve have to do with the 0C fault code?
- If my gas valve is sticking, is there a fix?
- Can the gas valve be tested to ensure it’s not faulty?
- How much will a new gas valve cost for my Viessmann boiler?
- What does moisture have to do with the 0C fault code?
- If the PCB is the problem, what is the best route forward?
- How much is it going to cost to replace the PCB on my Viessmann boiler?
What does the 0C fault code mean on my Viessmann boiler
When the 0C fault code is displayed on your Viessmann boiler’s control panel, it means the burner has gone into lockout mode.
Your boiler repair company is going to need to check for:
- Insufficient power supply
- Incorrect flame signal (present, even after the boiler has shut off)
Can the 0C fault be fixed on a DIY basis
It’s only on rare occasions that boiler faults can be fixed on a DIY basis; this isn’t one of those occasions.
The problem here could relate to either gas or electrics. Neither of these things should be fixed on a DIY basis.
Remember, resetting your boiler isn’t going to fix the problem. This reset is designed to be used after the problem has been rectified.
You’ll need to call a Gas Safe repair company. Once they’ve fixed the fault, they’ll reset your boiler which will clear the fault code from the display panel.
If I have an insufficient power supply, what should I do
Boiler problems can be tricky, because they don’t always relate to gas fault finding; sometimes it’s electrical. So, even the most experienced engineers have a hard time diagnosing the fault.
At EPHG, we know that, and that’s why we have a range of emergency services available. We have emergency Gas Safe engineers and emergency electricians on hand. Give us a call, and our team will be able to advise which service is most suitable service, to get your current problem fixed as soon as possible.
If the flame signal is still present after the boiler is switched off, what does this mean
Your boiler is controlled by the printed circuit board (PCB). The PCB gives signals to components to start and stop when needed. And, it gives these signals based on a range of sensors in your boiler; these monitor temperatures and pressures.
One of these sensors, gives a flame signal; it lets the PCB know when a flame is present.
In the case of the 0C fault code on your Viessmann boiler, a flame signal is present, even when it shouldn’t be.
The cause of the fault could be due to:
- Faulty flame sensor
- Broken gas valve
- Moisture on electronics
- Faulty PCB
How will my emergency boiler repair company know if the flame sensor is faulty
If the flame sensor is faulty, it might be giving signals to the PCB that are incorrect. For instance, it could be suggesting a flame is present, even when it isn’t. That’s going to lead the PCB into thinking that the boiler is dangerous, even though it’s operating correctly.
To test the flame sensor, your boiler engineer will use an electrical testing device called a multi-meter. This is going to determine whether the sensor is getting power. If the root cause of the fault is the sensor, it will need to be replaced.
After being replaced, your boiler engineer will be able to reset the boiler to clear the 0C fault code from the display panel.
What does the gas valve have to do with the 0C fault code
If the sensor is intact, then that suggests a flame is present when it shouldn’t be. One of the potential culprits, is the gas valve.
On the PCB’s command, the gas valve supplies fuel into the burner. It opens and closes as the demand for gas changes. But, these components can wear over time. And, when they do, they can stick.
If you have a sticking gas valve, it could be sticking partially open, even when the PCB is telling it to close. That’s going to mean that gas is still being allowed into the burner, even when it shouldn’t be. And, this could be dangerous.
If my gas valve is sticking, is there a fix
If your gas valve is sticking partially or fully open, there are ways to fix it. Your boiler repair company may be able to free the valve and stop it from sticking.
However, they’re going to want to make sure that the valve moves smoothly. If there’s a chance of the valve sticking again in the future, it’s likely they’ll suggest a replacement instead.
Can the gas valve be tested to ensure it’s not faulty
Not all gas valve faults relate to the component sticking. It may be that the valve’s communication with the PCB is being interrupted. This could be due to the component being faulty, or poor wiring/connections.
Your boiler engineer can start by testing the gas valve for power. That ensures it can communicate with the PCB. However, they’ll also need to test the wires and connections. Without a solid connection, it’s not going to be able to receive the correct signals from the PCB.
Small repairs can be made by your engineer; securing connections for instance. However, if the valve is showing signs of failure and wiring is in exceptionally poor condition, a replacement valve is likely to be the safest option.
How much will a new gas valve cost for my Viessmann boiler
Gas valves are not cheap components to replace. If you need a replacement, you should expect to pay around £250-300, including parts and labour. The job should take around one working day, but it’s likely your engineer will need to order the parts from their local supplier. So, your boiler should be up and running within 2-3 days.
After fitting the gas valve your engineer will need to reset your boiler. The PCB will recognise the gas valve fault is cleared thanks to the new component being fitted, and that’s going to clear the 0C fault code.
What does moisture have to do with the 0C fault code
Moisture and electrical components don’t mix, especially when it comes to older boilers. The electrical components in old boilers aren’t sealed as well as they are in newer ones. So, even the slightest sign of moisture, can cause big problems.
If your boiler engineer suspects moisture has caused damaged to the PCB, gas valve or any other component, it’s likely there’s a boiler leak.
Most likely, the leak has come from the pump. The pump’s seals degrade over time, and this can lead to small leaks. Any moisture that finds its way onto electronics, is going to cause problems.
So, before replacing important and expensive components, it makes sense to highlight the root cause of the problem. That way, you won’t be revisiting this problem again soon.
If the PCB is the problem, what is the best route forward
One of the most common problems we come across with boilers, are PCB faults. This could be anything from a complete failure due to old age or water damage, to a simple case of loose wiring and connections.
Your boiler engineer will use the same testing procedure they used for other electrical components. They’ll start with a quick visual inspection, checking the condition of wires, as well as securing any loose connections.
Whereby a visual inspection yields nothing, they’ll want to test the PCB. If the PCB doesn’t have power, or the supply of power to the PCB is intermittent, this is the most likely reason that the 0C fault code is being displayed on your boiler.
To fix the problem, the PCB will need to be replaced.
How much is it going to cost to replace the PCB on my Viessmann boiler
Unfortunately, PCBs are the most expensive part on a boiler to replace. You should expect the cost of the repair to be in the region of £500, including parts and labour. Like the gas valve, it’s likely your emergency boiler repair company will have to order in parts, so it will be 2-3 days until your boiler is running again.
With a repair bill of this size, you should always consult your engineer for the best route forward. If other expensive components are in poor condition (possibly due to water damage), replacing the boiler might be the more cost effective option in the long-term.
Ask your repair company to check the pump, fan and heat exchanger as a minimum, before making your decision.
Other Viessmann boiler issues
For more boiler issues regarding the Viessmann Boiler then please visit the Ideal Boiler Problems And Cures page.