Your Baxi boiler showing the 117 error code usually means the water pressure inside the system has climbed too high, causing the boiler to shut down safely to avoid damage. This common issue affects many UK homes and rental properties, leaving you without reliable heating or hot water until resolved.
What Does the Baxi Boiler 117 Error Code Mean?
The Baxi boiler 117 error code means your central heating system pressure is too high, normally above 2.5 to 3 bar. The boiler detects this and locks out to protect pipes, seals and other parts from strain or leaks. You will often notice the pressure gauge on the boiler sitting higher than the usual 1 to 1.5 bar when cold.
It is a helpful safety feature, but it can disrupt daily life if it keeps happening.
Seeing repeated pressure faults on your Baxi boiler can point to ongoing wear. Many of the homeowners and landlords we support at Eazy Heat discover that switching to a new boiler installation cuts repair costs and delivers better efficiency for years ahead.
What Causes the 117 Error Code On Your Baxi Boiler?
The 117 error code on your Baxi boiler most often comes from too much water entering the sealed system or parts that should manage pressure failing over time. Common triggers include overfilling, leaks from valves or problems with the expansion vessel.
Overfilling the System During Top Ups
Overfilling happens when you add too much water through the filling loop, often by leaving the valve open a bit too long or misreading the gauge. This pushes pressure well above safe levels, especially after bleeding radiators or during seasonal checks. Many UK households in hard water areas face this after routine maintenance.
How to Fix
- Turn off the boiler and let everything cool down fully to stay safe.
- Locate a radiator, preferably upstairs, and carefully bleed a small amount of water using the key until the pressure gauge drops back to around 1.2 to 1.5 bar.
- Check that the filling loop valves are fully closed and not dripping.
- Reset the boiler following the instructions in your manual and test the heating to confirm the error has cleared. Keep an eye on the gauge over the next few days.
Faulty Filling Loop Valve
A faulty filling loop valve can slowly leak mains water into the heating system even when you think it is closed. Worn seals or damage from regular use let extra water sneak in and build pressure gradually.
How to Fix
- Switch off the boiler at the isolator and close the mains water supply to the filling loop for safety.
- Inspect the flexible hoses and valves underneath the boiler for any drips or wetness when they should be closed.
- If you spot leaks, tighten connections gently or replace washers if you feel confident. Otherwise call a Gas Safe registered engineer straight away.
- After any repair repressurise carefully if needed, reset the boiler and monitor for stability.
Problems with the Expansion Vessel
The expansion vessel is like a cushion that absorbs extra pressure when water heats up and expands. If the air pressure inside it drops or the diaphragm fails, the system cannot handle normal changes and pressure spikes, triggering the 117 code.
How to Fix
- Turn off the boiler and release some pressure by bleeding a radiator until the gauge reads low.
- Check the expansion vessel pre-charge pressure with a suitable gauge if you have one, or ask an engineer to do this safely.
- Recharge the vessel with a bike pump or similar tool to the recommended level, usually around 0.75 bar when empty.
- Have a professional inspect or replace the vessel if recharging does not solve the issue, then reset and test the system.
When Should You Call a Professional for Your Baxi Boiler 117 Fault Code?
Simple pressure releases are fine for most people to try once, but if the fault returns quickly or you suspect valve or vessel problems, it is best to contact a Gas Safe registered engineer. They can carry out proper checks and repairs without risking further damage or voiding warranties.
How to Prevent Future 117 Errors On Your Baxi Boiler
Regular annual servicing keeps your system in good shape and catches pressure issues early. Check the gauge monthly and only top up when necessary. In hard water regions a scale inhibitor can reduce strain on components. UK boiler statistics show that properly maintained systems last longer and run more efficiently, helping control household costs amid ongoing energy pressures.
Replace an Ageing Boiler Before Pressure Problems Become Costly
If your Baxi boiler 117 error code keeps appearing, it may be more than just a one-off pressure issue. Recurring high-pressure faults are often a sign that key components such as the expansion vessel, filling loop, or internal seals are beginning to wear out. While repairs can solve individual faults, frequent breakdowns can quickly become expensive and leave you without heating or hot water when you need it most.
At Eazy Heat, we make replacing your boiler straightforward. We install high-quality, energy-efficient boilers for homeowners and landlords across the UK, providing a complete installation service from your initial online quote through to expert installation. Every new boiler comes with a market-leading 12-year parts and labour warranty, giving you long-term peace of mind and protection against unexpected repair costs.
Ready for a more reliable heating system? Use our online boiler quotation tool to receive a fast, transparent quote in just a few simple steps. We’ll help you replace your old boiler with a modern, efficient model that delivers dependable heating and hot water for years to come.
FAQs
How quickly can high pressure damage my heating system?
High pressure can stress pipes and seals quite fast if left unchecked, sometimes leading to leaks within weeks. Addressing the 117 code promptly helps avoid more expensive fixes down the line.
Does outside temperature affect boiler pressure readings?
Yes, colder weather can make pressure appear lower when the system is off, while heating up causes natural rises. Always check the gauge when the system is cold for the most accurate reading.
Are there grants available for upgrading an old boiler showing faults?
Depending on your circumstances and location, schemes like the Boiler Upgrade Scheme may offer support for moving to low carbon options. Our team at Eazy Heat can guide you on current UK incentives during a quote discussion.
Can landlord responsibilities include fixing repeated 117 errors?
Yes, landlords must ensure heating systems are safe and working. Persistent faults like high pressure issues should be repaired promptly to meet legal standards for tenant comfort and safety.
What is the typical lifespan of a Baxi boiler before pressure problems increase?
Most Baxi boilers give good service for 10 to 15 years with regular maintenance. After that, components like vessels and valves wear more noticeably, making upgrades a practical choice for many properties.