Modern boilers are clever machines. They constantly monitor their own performance and display fault messages when something isn’t quite right. While that can feel worrying, boiler error codes are simply the boiler’s way of helping you understand what’s gone wrong. In many cases, a quick check at home can get things running again. In others, it’s a sign you should speak to a Gas Safe engineer. Homeowners in Bordon, Whitehill, Liphook, Alton and Farnham often call us with the same questions, so this guide walks you through the essentials.
Quick checks you can do now
Before diving into specific boiler error codes, there are a few simple things worth checking. These quick steps often resolve minor faults safely and without tools.
- Is the boiler switched on and displaying power?
- Is your home’s electricity supply working normally?
- Do you have gas supply to the property (other gas appliances lighting normally)?
- Is the thermostat calling for heat?
- Are radiators or hot taps turned on for demand?
If everything above looks normal, it’s time to look at the specific code shown on your boiler display.
Understanding boiler error codes
Different manufacturers use different systems, but the purpose is the same: help you pinpoint what’s wrong. Worcester, Vaillant, Ideal and Baxi boilers commonly report similar types of issues, even if the numbers or letters differ. The following sections explain the typical categories of codes and what they usually indicate.
Ignition and flame failure codes
These are some of the most common boiler error codes homeowners encounter. Examples include F1, F28, E133 and similar combinations depending on the brand. They usually mean the boiler tried to light but couldn’t complete the ignition sequence.
- Check that your gas supply is on and other gas appliances work.
- Look at the boiler’s gas isolation valve to ensure it hasn’t been switched off accidentally.
- Reset the boiler once after checking the basics.
If you continue to see the code, this may indicate issues such as a faulty ignition probe, blocked condensate pipe, or low gas pressure – all jobs for an engineer. In colder months around GU35, GU34 and GU9, frozen condensate pipes are a common cause.
Pressure-related boiler error codes
Many boilers will display codes like F75, E119 or 0.0 bar readings when system pressure is too low. Low pressure usually happens when water has escaped from the system, either through normal radiator bleeding or a leak.
- Check the pressure gauge. Most boilers operate best between 1.0 and 1.5 bar.
- If the gauge is low, top up the system using the filling loop as shown in your boiler’s manual.
- Reset the boiler once the pressure is restored.
If pressure drops repeatedly, you may have a leak or a failing expansion vessel. That’s the point to call a professional, especially if you’re in an older property in the Bordon or Alton area.
Overheating and circulation codes
Boilers need steady water flow to move heat around the system. Codes relating to overheating or poor circulation, such as E20, H01 or similar, usually point to water not flowing correctly. Causes can include stuck pumps, sludge in the system or closed valves.
- Check that all radiator valves are open.
- Ensure the boiler has ventilation and the area around it is not blocked.
- Listen for unusual pump noises when the boiler attempts to fire.
If these issues persist, allow a qualified engineer to inspect the pump, heat exchanger and system water quality.
Sensors, probes and electrical fault codes
Error codes relating to components such as NTC sensors, fan speed sensors or internal wiring problems often start with letters like C, H, or specific multi-digit codes. These can appear when sensors fail, wiring becomes loose, or the fan cannot operate safely. These are not DIY repair tasks.
- Try a single boiler reset.
- Ensure the boiler casing has not been knocked or disturbed.
- Check for recent electrical work in the home that may have affected circuits.
If the code returns, an engineer will need to diagnose the exact component fault with specialist equipment.
When boiler error codes mean you should call an engineer
Some signs mean it’s best to stop troubleshooting and contact a professional straight away. Homeowners in Bordon, Whitehill, Liphook and surrounding areas often call us when they notice the following red flags:
- Repeated ignition failure after one safe reset
- Boiler pressure dropping daily
- Burning smells or unusual noises
- Visible leaks from the boiler or pipework
- Soot marks or signs of overheating
Here is a quick checklist to guide you:
- Have you checked power and gas supply?
- Have you topped up boiler pressure if required?
- Have you performed only one reset?
- Is the code still appearing?
If you answer yes to most of these and still have an issue, your boiler needs professional attention.
Keeping future boiler error codes to a minimum
Regular maintenance is the best defence against repeated faults. An annual service ensures the boiler is cleaned, inspected and tested for safe operation. Engineers can also spot early signs of part wear, system sludge or pressure problems before they trigger error codes. This is especially helpful for homes in the GU35, GU34 and GU9 areas where older pipework can make boilers more sensitive to circulation issues.
For friendly, local help with any boiler fault, book a visit today via https://www.embassygas.com/book.