Waking up to no hot water or heating is stressful enough – but when your Vaillant boiler flashes the F28 fault code, it can feel like a total mystery. Thankfully, it’s a fault I come across all the time, and in many cases, it’s quicker to fix than you might think.
I’m Tony from Advanced Heating and Plumbing, and in this blog, I’ll explain what the F28 code really means, what causes it, and what you can do next – whether that’s trying a few checks yourself or knowing when to call someone like me in.
Need a local expert to fix it fast?
If you’re in Watford, London, Hertfordshire or Middlesex, I can usually attend same day. I’ve been repairing Vaillant boilers for over 25 years and carry common parts to fix most F28 issues on the first visit.
📞 Call now on 0800 328 0449
Click here to get a quote onlineSo, What Does the F28 Fault Code Actually Mean?
In plain English? The boiler tried to light the gas to heat your home – and it didn’t work. Three failed attempts, and the system goes into lockout for safety.
It’s common in Vaillant ecoTEC models, especially during colder months when certain parts are under more strain. But don’t panic – it doesn’t always mean expensive repairs.
What Usually Causes It?
Here are the issues I typically see when I’m called out to an F28 fault:
🔹 1. No Gas Reaching the Boiler
This might sound obvious, but sometimes the issue is outside the boiler. If your gas meter has run out (prepay users), or if there’s been a supply issue locally, your boiler can’t ignite.
Tip: Try your gas hob. If that doesn’t work either, it’s probably a gas supply issue – not the boiler.
🔹 2. Frozen Condensate Pipe
One of the most common winter problems. If the pipe that removes condensation from the boiler freezes outside, it can back up the system and stop ignition.
What to look for: A gurgling boiler, or water trickling from the pipe.
What to do: Pour warm (not boiling) water gently over the pipe. Don’t force it.
🔹 3. Faulty Ignition Electrodes or Leads
These are the parts that spark the gas to ignite. If they’re worn, dirty, or misaligned, the boiler won’t light.
I carry replacements for these on the van, and in most cases, it’s a straight swap.
🔹 4. Gas Valve or PCB Issues
The gas valve controls the flow of gas. If it’s stuck or the PCB (printed circuit board) isn’t sending the right signals, the boiler won’t fire up. These are less common but more complex – and definitely something only a Gas Safe engineer should inspect.
Can You Fix It Yourself?
You can try these basic steps:
- ✅ Check the gas meter – credit, valve, and any shutoff
- ✅ Reset the boiler – usually a button on the front, hold for 5 seconds
- ✅ Look at the condensate pipe – any sign it’s frozen?
If it resets and the error comes back – or if you hear clicking but no ignition – stop there. Further attempts could make things worse or damage the boiler.
When to Call a Professional
That’s where I come in. I’m Tony, a Gas Safe registered heating engineer with over two decades of experience in fault-finding, especially on Vaillant models. You won’t get a call centre or generic advice – just a direct, honest diagnosis and repair from someone who’s fixed thousands of these.
Need Help? I Can Sort It – Fast and Fairly
- Clear fixed pricing – you’ll always know the cost upfront
- Same-day appointments whenever possible
- I stock parts for most F28 repairs
- Covering Watford, London, Middlesex and Hertfordshire
📞 Call now on 0800 328 0449
Book your visit or request a quote here
