The most common Baxi boiler error codes seen by homeowners and landlords across Edinburgh are E119 for low water pressure, E133 for ignition or gas supply issues, E110 for overheating, E125 for circulation problems and E160 for fan faults.
These codes lock the boiler out until the underlying issue is addressed, leaving the home without heating or hot water. Knowing what each one means helps you decide the next step quickly and safely.
At The Edinburgh Boiler Company we provide new boiler installations for homeowners and landlords across every Edinburgh postcode from EH1 to EH55 and surrounding towns such as Balerno, Bonnyrigg, Dalkeith, Linlithgow, Musselburgh, Penicuik and South Queensferry.
If your Baxi keeps throwing the same codes, a modern replacement can often prove more reliable and cost-effective over time.
Baxi Boiler Error Codes: A Quick Overview
Baxi boiler error codes give a clear indication of the fault so action can be taken without guesswork. The table below lists the codes most frequently reported on Duo-tec, Platinum, 600, 800 and EcoBlue models along with a short description of each.
| Code | Concise Description |
| E119 | Low water pressure in the system |
| E133 | Ignition failure or interruption of gas supply |
| E110 | Safety thermostat operated due to overheating |
| E125 | Circulation fault in the primary circuit |
| E160 | Fan or fan wiring fault |
| E28 | Flue NTC sensor, air pressure switch or blocked flue |
| E20 | Central heating NTC sensor fault |
| E50 | Hot water NTC sensor fault |
| E168 | PCB or general electronic fault |
What Causes Baxi Boiler Error Codes?
Baxi boiler error codes and how to fix them vary by the specific fault, yet most link back to pressure loss, ignition problems, poor circulation or a worn component. The sections that follow explain each common code in plain language, outline the usual causes and give numbered steps that are safe for a householder to try before calling a Gas Safe engineer.
E119 Low Water Pressure
E119 low water pressure means the system pressure has dropped below the minimum safe level of around 0.5 bar. The boiler shuts down to protect the heat exchanger and pump from running dry. This is the code most people can clear themselves.
Typical causes include a slow leak at a radiator valve or joint, water lost when radiators were bled, natural system loss over months, or a problem with the expansion vessel.
How to fix:
- Look at the pressure gauge on the front of the boiler. It should read between 1.0 and 1.5 bar when the system is cold.
- Find the filling loop, usually a flexible braided hose or two small valves under the boiler.
- Open the valves slowly to let mains water in until the gauge reaches about 1.2 bar.
- Close the valves tightly and press the reset button for a few seconds.
- Monitor the pressure over the following days. Repeated drops point to a leak that needs a Gas Safe engineer.
E133 Ignition Failure Or Gas Supply Interruption
E133 ignition failure or gas supply interruption means the boiler has tried to light and either no flame was established or the gas supply was interrupted. The appliance locks out for safety. Common causes are a frozen condensate pipe in cold weather, low or interrupted gas supply, dirty ignition electrodes, or a faulty gas valve.
This code appears more often during Scottish winters.
How to fix:
- Check that other gas appliances such as the hob still work. If they do not, inspect the gas meter for credit or contact your supplier.
- In freezing conditions, carefully pour warm (not boiling) water over the external condensate pipe to melt any ice, then wrap it with insulation.
- Press and hold the reset button for three to five seconds and wait for the boiler to attempt a restart.
- Attempt only one reset. If E133 returns, switch the boiler off and call a Gas Safe registered engineer who will test gas pressure, electrodes and the condensate route.
E110 Overheating
E110 overheating means the safety thermostat has detected that the water temperature inside the boiler has risen too high and has switched the system off. This protects internal components from damage. Usual causes include air locked in the system, a stuck or failing pump, low water pressure, closed radiator valves or a blocked heat exchanger.
How to fix:
- Turn the boiler off at the isolator and allow it to cool for at least thirty minutes.
- Check the system pressure and top it up to 1.0–1.5 bar if needed.
- Bleed any radiators that feel cold at the top to release trapped air.
- Restore power and try one reset.
- If the code reappears, contact a Gas Safe engineer. Persistent overheating often signals a circulation or heat-exchanger issue that needs professional diagnosis.
E125 Circulation Fault
E125 circulation fault means the boiler has detected that water is not moving properly through the primary heating circuit. Without circulation the boiler cannot deliver heat safely and locks out. Causes typically include a seized pump after a long period of inactivity, an air lock, sludge or debris in the system, or a faulty flow sensor.
How to fix:
- Confirm the system pressure sits between 1.0 and 1.5 bar and top up if necessary.
- Listen for the pump when the boiler tries to start. Complete silence or a loud grinding noise can indicate a seized impeller.
- Attempt one careful reset after checking pressure.
- If E125 persists, call a Gas Safe engineer. They may free the pump, clear blockages or recommend a power flush if the system is full of sludge. Repair costs usually range from £100 to £250 depending on the work required.
E160 Fan Or Fan Wiring Fault
E160 fan or fan wiring fault means the boiler cannot confirm that the fan is running at the correct speed. The fan is vital for removing combustion gases, so the appliance shuts down. Common causes are a worn fan motor, loose or corroded wiring, dust or debris restricting the fan, or a problem with the speed sensor.
How to fix:
- Check the external flue terminal for leaves, nests or other visible blockages and clear them if it is safe to do so from ground level.
- Ensure the area around the boiler is free of dust and items that could restrict airflow.
- Try one reset after any external clearance.
- If the code remains, switch the boiler off and arrange a Gas Safe visit. Fan replacement or wiring repairs must be carried out by a qualified engineer and typically cost between £150 and £350 including parts and labour.
E28 Flue Sensor Or Blocked Flue
E28 flue sensor or blocked flue means the boiler has detected a problem with the flue NTC sensor, the air pressure switch or a restriction in the flue or condensate pipe. Safe removal of gases is compromised, so the system locks out. Causes include a frozen or blocked condensate pipe, a faulty sensor, or debris in the flue terminal.
How to fix:
- Inspect the external flue terminal for any obvious obstruction and clear it carefully.
- In cold weather, thaw the condensate pipe with warm water if ice is present.
- Attempt one reset once any external issue is cleared.
- Persistent E28 requires a Gas Safe engineer to test the sensor, clean the flue path and confirm correct operation.
Ready For Reliable Heat Without The Recurring Codes?
Dealing with repeated Baxi boiler error codes can leave any home or rental property cold and frustrated, especially through the colder months. While many faults can be resolved, an older boiler that keeps displaying the same codes often ends up costing more in call-outs and parts than a straightforward replacement.
At The Edinburgh Boiler Company we specialise in new boiler installations for homeowners and landlords across Edinburgh and the surrounding areas. A modern high-efficiency system comes with a long manufacturer warranty, lower running costs and far fewer unexpected lockouts.
Request your free no-obligation new boiler quote today and move past the hassle of fault codes for good.
Frequently Asked Questions
How often should a Baxi boiler be serviced to help prevent error codes?
An annual service by a Gas Safe registered engineer is recommended. Regular checks keep electrodes clean, pressure sensors accurate and the fan free of debris, reducing the chance of common lockout codes appearing.
Can a recent power cut trigger Baxi boiler error codes?
Yes. A sudden power interruption can leave the control board in an unexpected state or allow air into the system. After power is restored a single reset often clears temporary codes, but any that return need proper investigation.
Do Baxi error codes differ between combi and system boilers?
The most frequently seen codes such as E119, E133, E110, E125 and E160 appear on both combi and system models. System boilers may display additional cylinder-related codes, yet the core pressure, ignition and circulation faults remain the same.
Is it usually cheaper to repair or replace a Baxi that keeps showing error codes?
If the boiler is more than twelve to fifteen years old and major components are failing, replacement often works out more economical over five years once energy savings and avoided repair costs are taken into account. A Gas Safe engineer can provide a clear comparison.
What should I do if I smell gas when a Baxi error code appears?
Turn the boiler off at the isolator, open windows, avoid using electrical switches and call the National Gas Emergency number 0800 111 999 straight away. Do not attempt further resets or any work on the appliance.
