Common questions about Viessmann codes · Search all brands by code or symptom
What is safe for you to do
Every code here follows the same safety rules. You can:
- press the reset button once, as your user guide shows;
- for low-pressure codes, top up the pressure with the filling loop, as your user guide shows;
- for ignition and flame-loss codes, check the gas is on at the meter and a prepayment meter has credit;
- thaw a frozen plastic condensate pipe outside with warm (not boiling) water;
- check the thermostat, timer and power to the boiler.
Never open the boiler casing. Only a Gas Safe registered engineer may work inside a gas boiler. Codes marked Engineer after one reset have no homeowner fix: reset once, then leave them to an engineer. Codes marked Safe checks first list the one check that relates to that code.
Vitodens 050-W (BPJC) and Vitodens 100-W (B1HA / B1KA)
Vitodens 050-W and 100-W boilers show a two-character code, e.g. F4. If 'R' or a reset symbol appears with it, the burner has locked out and needs a reset.
Source: Vitodens 100-W Type B1HA, B1KA Installation and Service Instructions; Vitodens 050-W Type BPJC Installation and Service Instructions, doc. 5677 216 GB (3/2015); 5513 085 GB (9/2014), 100-W pp. 62–65 'Fault display'; 050-W PDF pp. 46–49 'Fault display'. Open the manual (PDF) · 050-W manual (PDF) (Copy hosted by a UK trade site (no manufacturer-hosted copy found))
Ignition / flame
E5 Viessmann Vitodens 050-W/100-W
Engineer after one resetIgnition / flameWhat it means
Internal fault; the burner is blocked.
Likely causes
The ionisation electrode or its cables.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does E5 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, E5 is listed in the manufacturer's table as "Internal fault; the burner is blocked". Likely causes include the ionisation electrode or its cables. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
F3 Viessmann Vitodens 050-W/100-W
Engineer after one resetIgnition / flameWhat it means
A flame signal is already present when the burner starts.
Likely causes
Ionisation electrode or its cable.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does F3 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, F3 means a flame signal is already present when the burner starts. Likely causes include ionisation electrode or its cable. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
F4 Viessmann Vitodens 050-W/100-W
Safe checks firstIgnition / flameWhat it means
No flame signal detected: the boiler failed to light.
Likely causes
Gas supply pressure, the gas train, the ignition/ionisation electrode and leads, the ignition module, or a blocked condensate drain.
What you can safely do
Check another gas appliance such as the hob works, the gas meter valve is on and, on a prepayment meter, there is credit. In freezing weather, check the plastic condensate pipe outside: if it is frozen, pour warm (not boiling) water along it. Then press reset once. If the code comes back, stop resetting.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the gas supply is fine and the code returns after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does F4 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, F4 means no flame signal detected: the boiler failed to light. Check another gas appliance works, the meter valve is on and any prepay meter has credit, then reset once. If it returns, book a Gas Safe registered engineer.
F8 Viessmann Vitodens 050-W/100-W
Engineer after one resetIgnition / flameWhat it means
The fuel (gas) valve closes too late.
Likely causes
Gas train or its control paths.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Ignition and flame faults involve gas, so this is engineer-only.
What does F8 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, F8 means the fuel (gas) valve closes too late. Likely causes include gas train or its control paths. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Temperature / overheat
E3 Viessmann Vitodens 050-W/100-W
Engineer after one resetTemperature / overheatWhat it means
Fault in the safety chain; the burner is in a fault state.
Likely causes
The temperature limiter or its leads, or the control unit.
What you can safely do
Let the boiler cool for 20 to 30 minutes, then press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Overheat shut-downs are safety devices doing their job, so this is engineer-only.
What does E3 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, E3 is listed in the manufacturer's table as "Fault in the safety chain; the burner is in a fault state". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
F1 Viessmann Vitodens 050-W/100-W
Engineer after one resetTemperature / overheatWhat it means
Maximum flue gas temperature exceeded.
Likely causes
Low system water level, the circulation pump, or air in the system.
What you can safely do
Let the boiler cool for 20 to 30 minutes, then press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Overheat shut-downs are safety devices doing their job, so this is engineer-only.
What does F1 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, F1 means the maximum flue gas temperature exceeded. Likely causes include low system water level, the circulation pump, or air in the system. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
F2 Viessmann Vitodens 050-W/100-W
Engineer after one resetTemperature / overheatWhat it means
The temperature limiter (overheat stat) has tripped.
Likely causes
Low system water level, the circulation pump, air in the system, or the limiter and its cables.
What you can safely do
Let the boiler cool for 20 to 30 minutes, then press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code comes back after one reset. Overheat shut-downs are safety devices doing their job, so this is engineer-only.
What does F2 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, F2 means the temperature limiter (overheat stat) has tripped. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Flue / fan / air
F9 Viessmann Vitodens 050-W/100-W
Engineer after one resetFlue / fan / airWhat it means
Fan speed too low during burner start.
Likely causes
The fan, fan cables or supply, or the fan control.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the terminal looks clear and the code returns. Flue and fan faults can affect how combustion gases leave your home, so this is engineer-only.
What does F9 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, F9 is listed in the manufacturer's table as "Fan speed too low during burner start". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
FA Viessmann Vitodens 050-W/100-W
Engineer after one resetFlue / fan / airWhat it means
The fan did not reach its idle (stopped) state.
Likely causes
The fan, fan cables or fan control.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the terminal looks clear and the code returns. Flue and fan faults can affect how combustion gases leave your home, so this is engineer-only.
What does FA mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, FA means the fan did not reach its idle (stopped) state. Likely causes include the fan, fan cables or fan control. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
FC Viessmann Vitodens 050-W/100-W
Engineer after one resetFlue / fan / airWhat it means
Electrical fan control in the control unit is faulty.
Likely causes
Fan cable or the control unit.
What you can safely do
There is no homeowner check that fixes this code. Write down the full code, press reset once, and if it comes back leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the terminal looks clear and the code returns. Flue and fan faults can affect how combustion gases leave your home, so this is engineer-only.
What does FC mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, FC means the electrical fan control in the control unit is faulty. Likely causes include fan cable or the control unit. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Sensors / thermistors
10 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Outside temperature sensor short circuit. The boiler keeps running at a constant temperature.
Likely causes
Faulty outside sensor or lead.
What you can safely do
Nothing urgent: the boiler normally keeps heating without the outdoor sensor, using a fixed setting. Press reset once to see if it clears.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 10 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 10 is listed in the manufacturer's table as "Outside temperature sensor short circuit". Likely causes include faulty outside sensor or lead. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
18 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Outside temperature sensor lead break. The boiler keeps running at a constant temperature.
Likely causes
Broken lead or faulty sensor.
What you can safely do
Nothing urgent: the boiler normally keeps heating without the outdoor sensor, using a fixed setting. Press reset once to see if it clears.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 18 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 18 is listed in the manufacturer's table as "Outside temperature sensor lead break". Likely causes include broken lead or faulty sensor. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
30 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Boiler water temperature sensor short circuit. The burner is blocked.
Likely causes
Faulty boiler water sensor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 30 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 30 is listed in the manufacturer's table as "Boiler water temperature sensor short circuit". Likely causes include faulty boiler water sensor or wiring. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
38 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Boiler water temperature sensor lead break. The burner is blocked.
Likely causes
Broken lead or faulty sensor.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 38 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 38 is listed in the manufacturer's table as "Boiler water temperature sensor lead break". Likely causes include broken lead or faulty sensor. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
50 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Cylinder temperature sensor short circuit; no hot water heating (100-W manual).
Likely causes
Faulty cylinder sensor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 50 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 50 is listed in the manufacturer's table as "Cylinder temperature sensor short circuit; no hot water heating (100-W manual)". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
51 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Hot water outlet temperature sensor short circuit; no hot water heating.
Likely causes
Faulty outlet sensor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 51 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 51 is listed in the manufacturer's table as "Hot water outlet temperature sensor short circuit; no hot water heating". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
52 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Flow sensor short circuit. The burner is blocked.
Likely causes
Sensor connections, lead or the sensor.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 52 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 52 is listed in the manufacturer's table as "Flow sensor short circuit". Likely causes include sensor connections, lead or the sensor. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
58 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Cylinder temperature sensor lead break; no hot water heating (100-W manual).
Likely causes
Broken lead or faulty sensor.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 58 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 58 is listed in the manufacturer's table as "Cylinder temperature sensor lead break; no hot water heating (100-W manual)". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
59 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Hot water outlet temperature sensor lead break; no hot water heating.
Likely causes
Broken lead or faulty sensor.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 59 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 59 is listed in the manufacturer's table as "Hot water outlet temperature sensor lead break; no hot water heating". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
5A Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Flow sensor lead break. The burner is blocked.
Likely causes
Sensor connections, lead or the sensor.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does 5A mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, 5A is listed in the manufacturer's table as "Flow sensor lead break". Likely causes include sensor connections, lead or the sensor. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
b0 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Flue gas temperature sensor short circuit. The burner is blocked.
Likely causes
Faulty flue gas sensor or wiring.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does b0 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, b0 is listed in the manufacturer's table as "Flue gas temperature sensor short circuit". Likely causes include faulty flue gas sensor or wiring. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
b8 Viessmann Vitodens 050-W/100-W
Engineer after one resetSensors / thermistorsWhat it means
Flue gas temperature sensor lead break. The burner is blocked.
Likely causes
Broken lead or faulty sensor.
What you can safely do
Write down the full code. Check the boiler has power, then switch it off and on at its mains switch or press reset once. If the code comes back, leave it there: sensors are inside the casing.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Testing and replacing sensors means opening the casing, so this is engineer-only.
What does b8 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, b8 is listed in the manufacturer's table as "Flue gas temperature sensor lead break". Likely causes include broken lead or faulty sensor. There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
PCB / electrical
F0 Viessmann Vitodens 050-W/100-W
Engineer after one resetPCB / electricalWhat it means
Internal fault; the burner is blocked.
Likely causes
Control unit fault (the manual's fix is to replace it).
What you can safely do
Write down the full code. Check the boiler has power and nothing else in the house has tripped, then switch the boiler off and on at its mains switch or press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Board, wiring and gas valve checks mean opening the casing, so this is engineer-only.
What does F0 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, F0 is listed in the manufacturer's table as "Internal fault; the burner is blocked". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Fd Viessmann Vitodens 050-W/100-W
Engineer after one resetPCB / electricalWhat it means
Burner control unit fault.
Likely causes
Ignition electrodes and cables, strong electrical interference near the boiler, or the control unit.
What you can safely do
Write down the full code. Check the boiler has power and nothing else in the house has tripped, then switch the boiler off and on at its mains switch or press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Board, wiring and gas valve checks mean opening the casing, so this is engineer-only.
What does Fd mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, Fd is listed in the manufacturer's table as "Burner control unit fault". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
FF Viessmann Vitodens 050-W/100-W
Engineer after one resetPCB / electricalWhat it means
Burner control unit fault.
Likely causes
Ignition electrodes and cables, strong electrical interference near the boiler, or the control unit.
What you can safely do
Write down the full code. Check the boiler has power and nothing else in the house has tripped, then switch the boiler off and on at its mains switch or press reset once. If the code comes back, leave the boiler off.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code returns. Board, wiring and gas valve checks mean opening the casing, so this is engineer-only.
What does FF mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, FF is listed in the manufacturer's table as "Burner control unit fault". There is no homeowner fix for this. You can reset once, but do not open the casing; book a Gas Safe registered engineer and quote the full code.
Other / controls
A9 Viessmann Vitodens 050-W/100-W
Safe checks firstOther / controlsWhat it means
Communication error with an OpenTherm control; the boiler runs without it.
Likely causes
OpenTherm control connections, cable or the control itself.
What you can safely do
Check your room thermostat or programmer has power or fresh batteries and is set to call for heat. For a wireless control, follow its guide to reconnect it. Then press reset once.
When to call a Gas Safe engineer
Call a Gas Safe registered engineer if the code stays after you have checked the controls, or keeps coming back.
What does A9 mean on a Viessmann Vitodens 050-W and Vitodens 100-W boiler?
On a Viessmann Vitodens 050-W and Vitodens 100-W, A9 is listed in the manufacturer's table as "Communication error with an OpenTherm control; the boiler runs without it". Check the programmer, room thermostat batteries and any smart or wireless controls are working, then reset once. If it returns, book a Gas Safe registered engineer.
Common questions
About Viessmann fault codes
2 questions
Which Viessmann fault codes can I usually deal with myself?
On the Viessmann ranges in our guide, only these codes have a safe homeowner check first: A9 for lost control contact (check its power); F4 for gas supply or flame loss (check the meter and credit). Reset once afterwards. Every other code needs a Gas Safe registered engineer; never open the casing.
Where can I find the official fault code list for my Viessmann Vitodens 050-W and Vitodens 100-W?
Viessmann lists the fault codes in the installation and servicing manual for the Vitodens 050-W and Vitodens 100-W (document 5677 216 GB (3/2015); 5513 085 GB (9/2014)). Check your data badge matches this model first, because codes differ between ranges, and note the exact code before resetting.
Codes by type: Vitodens 050-W (BPJC) and Vitodens 100-W (B1HA / B1KA)
6 questions
Which Viessmann Vitodens 050-W and Vitodens 100-W fault codes relate to the flue, fan or air supply?
On the Viessmann Vitodens 050-W and Vitodens 100-W, the manufacturer's table has 3 flue, fan or air supply codes: F9, FA, FC. None of these has a homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Viessmann Vitodens 050-W and Vitodens 100-W fault codes mean the boiler will not light or loses its flame?
On the Viessmann Vitodens 050-W and Vitodens 100-W, the manufacturer's table has 4 ignition or flame codes: E5, F3, F4, F8. For F4, first check the gas meter, prepay credit and another gas appliance, then reset once. The others need a Gas Safe registered engineer.
Which Viessmann Vitodens 050-W and Vitodens 100-W fault code relates to controls or other faults?
On the Viessmann Vitodens 050-W and Vitodens 100-W, the manufacturer's table has one controls or other code, A9. Check the programmer, room thermostat batteries and any smart or wireless controls are working, then reset once. If it returns, book a Gas Safe registered engineer.
Which Viessmann Vitodens 050-W and Vitodens 100-W fault codes point to a control board or electrical fault?
On the Viessmann Vitodens 050-W and Vitodens 100-W, the manufacturer's table has 3 control board or electrical codes: F0, FF, Fd. None of these has a homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Viessmann Vitodens 050-W and Vitodens 100-W fault codes point to a temperature sensor fault?
On the Viessmann Vitodens 050-W and Vitodens 100-W, the manufacturer's table has 12 temperature sensor codes: 10, 18, 30, 38, 50, 51, 52, 58, 59, 5A, b0, b8. None of these has a homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Which Viessmann Vitodens 050-W and Vitodens 100-W fault codes mean the boiler is overheating?
On the Viessmann Vitodens 050-W and Vitodens 100-W, the manufacturer's table has 3 overheat codes: E3, F1, F2. None of these has a homeowner fix beyond one reset. Do not open the casing; book a Gas Safe registered engineer and quote the full code.
Code still showing? Book a repair
CombiCert Ltd is a Gas Safe registered business (621146) in Telford, Shropshire. Our team of 2 to 5 engineers is led by director and Gas Safe engineer Peter Jefferson. Boiler repair from £90 + VAT, parts quoted separately.
Send us the make, model and the exact code on WhatsApp and we will tell you what we need to check.
Explanations are written by CombiCert from the manufacturer manuals listed, which you should check for your exact model. This page is general information, not a diagnosis. If you smell gas, call 0800 111 999.