How to Fix E118 Baxi Boiler Fault Code?

What Is the E118 Fault Code on a Baxi Boiler?
LOW Water pressure (<0.5 bar)

When your Baxi boiler displays the E118 boiler fault code, it alerts you to low system water pressure.

The boiler has dropped below the minimum safe pressure (typically under 1.0 bar), so it has shut down to avoid internal damage. If you see "E118" on the display, your boiler effectively asks for a top-up!

If the pressure drops below this threshold, you may experience:

• Cold radiators and no hot water
• Intermittent heating or temperature fluctuations
• The boiler is not igniting, or a total system shutdown

Low boiler pressure can result from natural pressure loss, routine radiator bleeding, or (most often) a small system leak.

Call a professional for a reliable boiler repair service when you notice any signs.

What Causes the E118 Boiler Fault Code?

Several issues can trigger the Baxi boiler E118 fault. However, identifying the root causes early can help you avoid future breakdowns and significantly extend your boiler's lifespan.

• The most common culprit. Tiny leaks in radiators, valves, or pipework gradually reduce water pressure.
• Often, leaks occur after bleeding a radiator or recent boiler maintenance.

• A malfunctioning pressure valve may fail to keep the system pressurised.
• The valve can release water when it shouldn't, leading to slow pressure loss.

• Regular bleeding removes trapped air but can also lower system pressure.
• If pressure isn't topped up, the E118 boiler code may appear.

• Microscale leaks in pipework are hidden from view.
• The recent system draining without complete depressurisation.

If you’d like a wider overview of common Baxi boiler faults and how they’re typically resolved, read our complete guide to 'common Baxi boiler problems and expert solutions' to compare more fault codes and troubleshooting steps.

Symptoms of the Baxi E118 Error Code – What to Watch Out For

Not sure if your boiler is throwing up the E118 fault? Here are some clear signs your Baxi boiler is struggling with low pressure, a common issue in many London homes, especially older properties or flats with ageing heating systems:

• E118 Error Code on the Display Panel
  The most obvious sign is that your boiler's control panel will clearly show the "E118" code, alerting you to a pressure-related fault.
• Pressure Gauge Drops Below 1 Bar
  Keep an eye on the pressure gauge. If it dips under 1.0 bar, your system doesn't have enough water pressure to function properly, triggering the E118 error.
• Radiators Feel Cold or Only Partially Warm
  Low pressure affects water circulation, meaning radiators may heat unevenly or not at all. You'll likely feel cold spots or notice slow warming.
• Hot Water Suddenly Cuts Out or Isn't Available
  Inconsistent water pressure can lead to disruptions in your hot water supply, especially noticeable during showers or while using taps.
• Boiler Fails to Start or Repeatedly Turns Off
  The boiler may attempt to fire up only to shut down shortly after. This on-off cycling is a safety feature when the pressure is too low for safe operation.
• Low Pressure Warning Light (on Compatible Models)
  Some Baxi boilers include an additional low-pressure warning light, giving you an extra visual cue that something's wrong.

If you're experiencing one or more of these symptoms, don't ignore them. The longer you leave low boiler pressure unresolved, the more strain you place on your system, and the more likely you'll face further damage or costly repairs.

Check out our blog: "Invest in Boiler Repairs Now to Avoid Bigger Problems Later", a must-read for every homeowner.

Fixing the E118 Boiler Fault

Most E118 main boiler faults can be resolved by topping up the water pressure using the filling loop. Here's how to safely repressurise your boiler system:

• Locate the gauge (usually on the boiler's front panel or beneath the casing).
• The needle should rest between 1.0 and 2.0 bar (the ideal range).
• If it's under 1 bar, you need to add water.

• Find the filling loop (a flexible silver/metal hose, typically beneath the boiler).
• Locate both levers (or tap handles) on each end.
• Open both levers slowly. You should hear water entering the system.
• Watch the pressure gauge. When it reaches 1.5 bar, close both levers fully.

• Check all visible radiators, valves, and pipework for signs of water.
• Pay close attention to areas with corrosion, green or white residue, or visible dripping.
• If you spot a leak, arrange for immediate repair to prevent recurring pressure loss.

• Turn off the boiler via the power button or at the main switch.
• Wait a couple of minutes, then restart.
• The E118 Baxi fault should clear if the pressure stabilises and no further issues are detected.

• Ensure the system holds pressure. Recheck the gauge daily for a week.
• Drastic drops indicate an ongoing leak or potential valve issue.
• Persisting E118 errors require professional attention.

When to Call a Professional?

If the E118 boiler fault returns after repressurising or you can't find the source of a pressure loss, contact a leak repair expert.

Persistent low pressure could mean:

• Hidden leaks in floors, wall cavities, or underfloor heating circuits
• A faulty safety valve or pressure sensor

Professional leak detection teams use advanced, non-invasive technology (tracer gas, thermal imaging, and acoustic sensors) to pinpoint hidden leaks without damaging your property.

Always consult a gas heating registered engineer for persistent boiler pressure problems or if you feel unsure during any step. Safety comes first.

Preventing Future E118 Boiler Fault

Take these simple preventative steps to avoid repeat occurrences of the E118 Baxi error:

• Regularly check your boiler pressure (especially after bleeding radiators).
• Watch for wet patches beneath radiators or pipe runs.
• Book annual boiler servicing to catch leaks early and ensure all valves work correctly.
• Invest in professional boiler leak detection if you repeatedly need to repressurise your system.

Expert Help from Serviceteam

At Serviceteam, we specialise in finding and fixing the root causes of heating inefficiency and persistent error codes. Our gas heating engineers and leak detection specialists can:

• Repressurise your boiler safely
• Detect and repair hidden leaks using the latest technology
• Service or replace faulty boiler valves, sensors, or pipework
• Provide a 12-month guarantee on all repair work

Don't put up with a cold home or worrying fault codes. For expert help with E118 Baxi boiler faults, call Serviceteam today or book online for a rapid response across London and the South East. Do not forget to check our boiler error codes blog section.

Take Control of Your Boiler's Health

Fixing an E118 Baxi boiler fault is straightforward for most homeowners and landlords. With regular inspections, timely leak repairs, and annual servicing when needed, you can ensure your boiler runs smoothly and efficiently throughout the year.

The Serviceteam is just a phone call away for persistent problems or guidance through the process.