Seeing a Baxi E118 fault usually means your boiler pressure has dropped too low. As a safety measure, the boiler shuts down to help prevent damage. In many cases, restoring the correct pressure resolves the fault.
- Content Guide
- » What Does the Baxi E118 Fault Mean?
- » What Causes a Baxi E118 Fault?
- - System leaks
- - Faulty pressure relief valve
- - Bleeding radiators
- - Other causes
- » Common Signs of an E118 Fault
- » How to Fix a Baxi E118 Fault
- - Step 1: Check the pressure gauge
- - Step 2: Repressurise using the filling loop
- - Step 3: Check for leaks
- - Step 4: Reset the boiler
- - Step 5: Monitor the pressure
- » When to Call a Gas Safe Engineer
- » How to Prevent the Fault Returning
- » Need Help With a Baxi E118 Fault?
What Does the Baxi E118 Fault Mean?
The E118 fault code indicates low system water pressure. Most Baxi boilers operate best between 1.0 and 2.0 bar. If pressure falls below the safe level, the boiler may stop producing heating and hot water until the pressure is restored.
You may notice:
- Cold radiators
- No hot water
- Boiler failing to ignite
- Heating cutting in and out
What Causes a Baxi E118 Fault?
The most common causes include:
System leaks
Small leaks from radiators, valves or pipework slowly reduce system pressure.
Faulty pressure relief valve
A worn or faulty pressure relief valve can allow water to escape, causing repeated pressure loss.
Bleeding radiators
Removing trapped air lowers system pressure. If you don't top the pressure back up afterwards, the E118 fault can appear.
Other causes
Less obvious leaks inside the heating system or recent maintenance work can also cause pressure loss.
Common Signs of an E118 Fault
Typical symptoms include:
- E118 displayed on the boiler
- Pressure gauge below 1 bar
- Cold or partly heated radiators
- Hot water cutting out
- Boiler repeatedly shutting down
If the pressure keeps falling after repressurising, there is likely to be an underlying fault that needs investigating.
How to Fix a Baxi E118 Fault
Step 1: Check the pressure gauge
Locate the pressure gauge and confirm whether it has dropped below 1 bar.
Step 2: Repressurise using the filling loop
Open the filling loop slowly while watching the gauge. Stop when the pressure reaches around 1.5 bar, then close both valves. Avoid overfilling the system.
Step 3: Check for leaks
Inspect visible radiators, valves and pipework for dripping water, corrosion or damp patches.
Step 4: Reset the boiler
Restart the boiler once the pressure has been restored. If low pressure was the only issue, the fault should clear.
Step 5: Monitor the pressure
Check the pressure over the next few days. If it continues to fall, the system may have a leak or faulty component.
When to Call a Gas Safe Engineer
If the E118 fault returns shortly after repressurising, don't keep topping the system up.
Repeated pressure loss often points to:
- Hidden leaks
- A faulty pressure relief valve
- A pressure sensor fault
- Another heating system problem
A Gas Safe engineer can identify the cause and carry out the necessary repair. If repressurising doesn't solve the problem or the pressure keeps dropping, book a professional boiler repair service to identify the underlying fault.
How to Prevent the Fault Returning
Reduce the chances of another E118 fault by:
- Checking boiler pressure regularly
- Looking for signs of leaks
- Repressurising after bleeding radiators
- Booking annual boiler servicing
Routine maintenance helps spot small issues before they become expensive repairs.
Need Help With a Baxi E118 Fault?
If your boiler keeps showing the E118 fault or pressure drops repeatedly, it's worth getting the system checked. A proper diagnosis will identify whether the problem is a leak, faulty valve or another component before it causes further breakdowns.
Book a boiler repair with Serviceteam and our Gas Safe engineers will diagnose the cause and carry out the required repair. If you're dealing with a different error, see our complete guide to Baxi boiler fault codes.
