Biasi Boiler Error Codes: Causes & Fixes

If your Biasi boiler is displaying an error code on its screen, don’t panic. Understanding Biasi boiler error codes is the first step to getting your central heating system or hot water back up and running quickly.

These fault codes are designed by the manufacturer to pinpoint specific issues in popular models like the Biasi Riva Compact, Advance Plus, ActivA, Garda HE, and Inovia.

This guide covers the most common Biasi boiler fault codes, along with their causes and practical fixes. Many issues can be resolved with simple troubleshooting, while others require a Gas Safe registered engineer for safety reasons.

What Should You Do When a Biasi Boiler Fault Code Appears?

When a Biasi boiler fault code appears, the boiler often enters lockout mode for safety. Start by noting the exact code, for example ER 01 or ER 03 with a flashing light. Try a simple reset by pressing and holding the reset button for 3 to 5 seconds, checking your model manual for the exact sequence.

If the code persists, avoid repeated resets, since this could indicate a deeper issue. Always prioritise safety. If you smell gas, turn off the supply and call the National Gas Emergency Service on 0800 111 999.

How Do You Reset a Biasi Boiler Safely?

To reset a Biasi boiler safely, locate the reset button on the front panel, then press and hold it for 5 to 10 seconds until the display changes or the boiler restarts. Wait up to 10 minutes for the ignition sequence to complete.

Never reset more than twice in a row. Repeated failed ignitions can flood the combustion chamber with gas.

What Does the E133 Error Code (or ER01 with No Flame) Mean on a Biasi Boiler?

Error code E133, or ER01 shown with a red lockout light, means the boiler has failed to detect a flame after several ignition attempts. In short, it’s an ignition lockout.

Common Causes of E133 / ER01

• Frozen condensate pipe, very common in winter
• No gas reaching the boiler, whether the meter is off, prepayment credit has run out, or the gas pipe itself is frozen
• Faulty ignition electrode or spark generator
• Gas valve not opening correctly

How to Fix E133: Frozen Condensate Pipe (DIY)

1. Find the white plastic condensate pipe outside, usually 22mm or 32mm, exiting the wall.
2. Pour lukewarm water, never boiling, over the frozen section until it thaws.
3. Reset the boiler once water flows freely.
4. Wrap the pipe with lagging or heat tape to prevent it happening again.

How to Fix E133: No Gas Supply (DIY)

1. Check other gas appliances, such as the hob or fire. If they don’t work either, top up your prepayment meter or call your supplier.
2. Look for a gas isolation valve under or beside the boiler and make sure it’s open, with the handle in line with the pipe.
3. If the outside meter is frozen, gently warm it with a hot water bottle or hairdryer.

How to Fix E133: Electrode or Gas Valve Fault (Gas Safe Engineer Needed)

A qualified engineer will clean or replace the ignition electrode, typically £120 to £220, or test and replace the gas valve, typically £250 to £450.

What Does the A01 Error Code Mean on a Biasi Boiler?

Error code A01 means ignition failure. It carries the identical meaning to E133 or ER01 on newer firmware models.

What Does the E110 or A02 Error Code Mean on a Biasi Boiler?

Error code E110 or A02 means the safety thermostat has tripped because the boiler has overheated.

Common Causes of E110 / A02

• Low system water pressure
• Seized or slow-running pump
• Blocked primary heat exchanger, from sludge or limescale
• Airlock in the system

How to Fix E110: Low Water Pressure (DIY)

1. Find the filling loop, either a flexible silver hose or a built-in key under the boiler.
2. Slowly open both valves until the pressure gauge reaches 1.2 to 1.5 bar.
3. Close the valves tightly and reset the boiler.

How to Fix E110: Pump or Circulation Problem (Engineer)

An engineer may need to free the pump, fit a new one at around £280 to £420, or carry out a powerflush at around £350 to £600.

What Does the E118 or A03 Error Code Mean on a Biasi Boiler?

Error code E118 or A03 means low primary circuit water pressure, below 0.4 to 0.6 bar.

Common Causes of E118 / A03

• A leak on the heating system, or the pressure relief valve dripping outside
• Recently bled radiators without repressurising afterwards
• A faulty pressure sensor

How to Fix E118: Top Up Pressure (DIY)

Follow the same repressurising steps as E110 above. Check outside for water dripping from the orange pressure relief pipe. This usually means a faulty expansion vessel or pressure relief valve, which needs a professional to replace.

What Does the A04 or E154 Error Code Mean on a Biasi Boiler?

Error code A04 or E154 means a problem with the fan or air pressure switch, often shortened to APS, and the boiler cannot confirm correct ventilation.

Common Causes of A04 / E154

• Blocked or obstructed flue terminal, from leaves, snow, or a wasp nest
• Faulty fan motor
• Broken air pressure switch or blocked venturi

How to Fix A04: Blocked Flue (DIY if Safe)

Carefully clear any visible debris from the external flue terminal. Do not climb ladders if it isn’t safe to do so.

How to Fix A04: Fan or APS Fault (Engineer)

A replacement fan typically costs £220 to £380, and a new air pressure switch typically costs £120 to £200.

What Does the E164 or A07 Error Code Mean on a Biasi Boiler?

Error code E164 or A07 means a fault with the domestic hot water temperature sensor, or excessive hot water temperature.

Common Causes

• A failed hot water NTC sensor
• Heavy limescale in the plate heat exchanger, common in hard water areas

Fix

Sensor replacement typically costs £140 to £250, or the secondary heat exchanger may need descaling or a powerflush.

Similar Codes on Other Boiler Brands

If you don’t have a Biasi boiler, similar lockout and sensor faults show up under different codes on other makes.

For a comparable ignition or lockout fault, alpha boiler error codes explained covers the equivalent codes on Alpha boilers.

Worcester Bosch owners seeing comparable hot water or flow issues can check Worcester Bosch error code solutions for their EA code, or Worcester Bosch C6 error code explained if the fault relates to flow or pressure detection instead.

Related Issues Worth Checking

If your radiators are heating unevenly, hot at the top and cold at the bottom, rather than showing an error code, that’s usually air in the system rather than a boiler fault. radiator temperature issues explained covers bleeding and balancing steps for that specific symptom.

If your Biasi is getting older and facing repeat faults, it may be worth comparing against other brands before repairing again. Worcester Bosch boiler reviews and comparisons is a useful benchmark for reliability and running costs if you’re weighing up a replacement.

FAQs

Do Biasi boilers show different codes on older vs newer models?

Yes. Older Biasi models, such as the Riva Plus and Garda, use ER01, ER02 and similar codes, while newer Inovia and Advance Plus models use E-codes such as E133, E110 and E118. The underlying problems are the same.

Will my Biasi boiler lose its warranty if I reset it myself?

No. Resetting and repressurising are considered normal user actions and don’t affect the warranty. Only opening sealed components or gas-carrying parts would invalidate it.

Why does my Biasi boiler keep showing an error code after an engineer visit?

The most common reason is an intermittent fault, such as loose wiring or a failing PCB, or a secondary issue that wasn’t spotted on the first visit. Ask for a follow-up under the original call-out warranty, since most companies give 30 days.

Are Biasi parts easy to get in the UK?

Yes. Biasi spare parts are widely stocked by Parts Center, HRPC, and most local merchants. Popular items like pumps, PCBs, and sensors are usually available on next-day delivery.

Can smart thermostats cause error codes on Biasi boilers?

Very rarely, but incorrect wiring of controls such as Nest, Hive or Tado can cause communication errors or prevent the boiler firing. Always use a qualified installer for smart control upgrades.

Can I identify a Biasi fault code without the manual?

Often, yes. Newer digital displays on models like the Inovia show a short description alongside the code. Older models with just a number or flashing light are harder to interpret without a code table, so it’s worth keeping a photo of the manual’s fault code page or bookmarking a guide like this one.

Does a Biasi fault code always mean I need a paid repair?

No. A frozen condensate pipe and low system pressure account for a large share of Biasi lockouts and are both free, safe DIY fixes. Ignition, gas valve, pump, and sensor faults are the ones that need a Gas Safe registered engineer.