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Vaillant F28 Fault Code Repair

Welcome to the fault-codes section of this site. The following table or page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. You may be guided through the fault finding sequence or steps, for rectifying your boiler with this fault code. Suggested repair solutions may be provided by a link to a repair page. NB Some fault codes are only applicable to a specific range of boilers only.

Vaillant F28 Fault Code Repair

Models applicable to:

Ecotec Pro/Plus, Turbomax

F.28 Meaning

Failure during start-up: ignition unsuccessful


  • Gas meter defective or gas pressure regulator has triggered,
  • air in gas,
  • gas flow pressure too low,
  • thermal isolator device (TAE) has triggered,
  • condensate duct blocked,
  • incorrect gas restrictor,
  • incorrect ET gas valve,
  • fault on the gas valve,
  • multiple plug on PCB incorrectly plugged in,
  • break in cable harness,
  • ignition system (ignition transformer, ignition cable, ignition plug, ignition electrode) defective,

vaillant electrode 0020133816

vaillant electrode 0020133816

  • ionisation current interrupted (cable, electrode),
  • incorrect earthing of boiler,
  • electronics defective


1 . Check the gas meter has not been turned of accidentally or run out of credit if a prepayment meter. The number of times the gas lever has been found accidentally in the off or partially off position is surprising to clients.

E6 Gas MeterU6 gas Meter

2. You may need to press reset button upto 3 times just in case it is a one off occurrence or for the gas supply to re-estabilish. Make sure to keep an eye on future occurrences as this may show that are more deeper issues with the boiler that may require a heating professional to have a look at the boiler.

Ecotec Old F28 Reset Image
Vaillant F28. No 3 Reset Button
Vaillant Ecotec New Display F28 Reset Button
Vaillant Ecotec New F28 , No 3 Reset Button.

3. If the weather is extremely cold make sure your condensate pipe has not frozen or got blocked. When weather is normally, blocked condensate pipework can be cause by debris or blocked pathways further down the line

Disclaimer: Above video is by Worcester Bosch and some parts may not be applicable to your boiler.

4. Another common problem is the gas valve sticking due to the internal lubrication / seals hardening in cold weather, giving a the gas valve a gentle tap with a rubber object may allow it to free up.This technique can be improved by tapping while the boiler is in the process of ignition.Please note, this solution can only be carried out by a gas engineer as it requires the boiler case being removed in order to access the gas valve. Secondly as this is a gas appliance, it should only be done by a gas heating engineer.

5. Get a qualified gas engineer to check internal wiring and state of boiler

Statistical Chances of Faults:

Following are the likely chances of certain faults from high to low.

~39% chance of the gas valve being at fault.
~32% chance of the gas supply being at fault
~28% chance of other reasons causing the fault

Preventing frozen condensate pipework:

There are a few solutions to solving frozen condensate pipework. These are as follows

  • The best solution is to make sure discharge pipework is run internally if possible.
  • If run externally make sure it is of large diameter pipe size ie 32mm and 40mm (insulated if possible or required)
  • Insulate smaller pipes with suitable exterior grade insulation
  • Use trace heating if required and installed according to the trace heating manufacturers recommended instructions.


This fault code is known to show up with fault code F27. The difference between F27 and F28 is that F27 is failure immediately after ignition, whereas F28 is complete failure to ignite.

Part Numbers

Vaillant Turbomax Gas Valve 053210

Suitable for:
Vaillant VU 242 E
Vaillant ThermoCompact VU 182 E
Vaillant ThermoCompact VU 242 E
Vaillant ThermoCompact VU 282 E
Vaillant ThermoCompact VU 282 E
Vaillant TurboMax VUW 242 B
Vaillant TurboMax VUW 242 E
Vaillant TurboMax VUW 282 E
Vaillant VU 182 E
Vaillant VU 282 E
Vaillant VUW 242 E
Vaillant VUW 282 E

Vaillant EcoTec Plus Gas Valve 0020110996

Suitable for:
Vaillant EcoTec Plus 624 VU 246/3-5
Vaillant EcoTec Plus 624 VU 246/3-5 R1
Vaillant EcoMax 828
Vaillant EcoTec Plus 831 VUW 316/3-5
Vaillant EcoTec Plus 831 VUW 316/3-5 R1

Vaillant EcoTec Plus Gas Valve 0020110997

Suitable for:
Vaillant EcoTec Plus 612 VU 126/3-5
Vaillant EcoTec Plus 612 VU 126/3-5 R1
Vaillant EcoTec Plus 615 VU 156/3-5
Vaillant EcoTec Plus 615 VU 156/3-5 R1

Vaillant Turbomax Plus – Pro Gas Valve 114189

Suitable for:
Vaillant TurboMax Pro 24/28
Vaillant TurboMax Plus 824/828
Vaillant TurboMax Plus 837
Vaillant ThermoCompact 615/620/624/628/637

Vaillant Printed Circuit Board (PCB) 0020132764

Suitable for:
Vaillant Ecotec Pro 24 (up to 2012)
Vaillant Ecotec Pro 28 (up to 2012)
Vaillant Ecotec Plus 824 (up to 2012)
Vaillant Ecotec Plus 831 (up to 2012)
Vaillant Ecotec Plus 837 (up to 2012)
Vaillant Ecotec Plus 937 (up to 2012)

Vaillant Turbomax Plus Printed Circuit Board (PCB) 0020034604

Suitable for:
Vaillant TurboMax Pro 24E
Vaillant TurboMax Pro 28E
Vaillant TurboMax Plus 824
Vaillant TurboMax Pro 828
Vaillant TurboMax Plus 837

Vaillant EcoTec Plus PCB 0020036861

Suitable for:
Vaillant EcoTec Plus 415
Vaillant EcoTec Plus 418
Vaillant EcoTec Plus 428
Vaillant EcoTec Plus 438

F28 Please note,a qualified gas engineer is required to work on gas appliances, however basic checks such as making sure the gas is turned on can be carried out by home owners or tenants. If you are looking for an engineer to carry out a repair on your boiler, feel free to use the Vaillant Pro finder section on our website. Remember Vaillant Pros can diagnose F28 problems quickly and efficiently.<

1 thought on “Vaillant F28 Fault Code Repair”

  1. If you come to this page to solve your F28 problem and the solutions we have mentioned help you achieve that, please feel free to let us know what could be improved based on the path you took or alternatively what solution worked for you in the end.

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Disclaimer: Information on this website is provided for informational purpose therefore we cannot accept liability for subsequent problems. All repair tasks should be carried out by qualified trades people. We may also receive commission payments when you are taken to external websites and complete purchases from third party sellers, once you leave our site, we cannot be held liable for your purchases.