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If your Baxi boiler is showing the E43 error code, it means the system has identified a fault with either the gas valve or fan two critical components involved in safe ignition and combustion. Baxi boilers are a type of heating equipment that rely on an electronic control system to monitor and manage their operation. Like other electronic mechanical devices, Baxi boilers can experience faults that trigger error codes such as E43. At 0800 Homefix, we regularly resolve Baxi E43 faults to get your heating and hot water systems back up and running safely.
This guide explains the meaning of the Baxi E43 error, its likely causes, and how our Gas Safe engineers can provide lasting solutions.
What Is the Baxi E43 Fault Code?
The E43 fault code appears on Baxi boilers when there is a problem with:
The modulating gas valve, which regulates gas supply
The fan, which ensures proper airflow through the combustion chamber
When a malfunction is detected by the boiler’s control system, the error coding process generates specific error codes, such as E43, which are then shown on the control display screen. This allows users and technicians to quickly identify and diagnose faults.
You might encounter this fault under the following search terms:
Baxi E43 error
Gas valve fault Baxi E43
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Baxi boiler showing E43
E43 on Baxi boiler
It typically affects Baxi Platinum, Duo-tec, and Main Eco boiler models. Different boiler models may display error codes in slightly different ways, depending on their control system and control display screen design.
Common Causes of the E43 Error: Flue Gas Sensor Issues
Stuck or damaged gas valve: Prevents the boiler from safely modulating the gas supply.
Fan not spinning or running too slowly: Reduces airflow and triggers a safety shutdown.
Faulty PCB (Printed Circuit Board): Miscommunication between components.
Blocked flue or air intake: Leads to inadequate air flow.
Loose electrical connections: Especially around the fan or gas valve wiring.
Faulty air pressure switch: Prevents safe venting of exhaust gases, causing the boiler to lock out for safety.
Air pressure switch issues: Incorrect air pressure readings can stop the boiler from operating safely.
Gas valve relay problems: Loss of electrical contact on the gas valve relay can disrupt gas flow and cause malfunctions.
Minimum pressure switch faults: If the minimum pressure switch fails, the boiler may not detect safe system pressure, triggering the E43 error.
Differential pressure switch faults: A malfunctioning differential pressure switch (also known as a micro-switch) can cause incorrect pressure readings and error codes.
Supply voltage drops: Fluctuations or drops in supply voltage can disrupt electronic control signals and lead to error codes like E43.
Signs of the E43 Fault
Boiler won’t ignite or frequently cuts out
Loud humming or whirring from the fan
Error display shows Baxi E43 error this error may appear on the control screen, or if a display is not present, it may be indicated by the corresponding LED indicator.
The control display provides fault codes, such as E43, to help users and engineers diagnose the issue.
Heating and hot water unavailable
A short attempt at ignition, followed by shutdown
Initial Checks You Can Do
Before starting any troubleshooting, always consult your boiler manual for specific instructions and safety information.
Reset the boiler using the control panel (once only)
Listen to see if the fan activates during start-up
Ensure the boiler flue isn’t blocked
Check if the temperature sensor is functioning correctly; sensor testing may be required to diagnose faults
⚠️ Any inspection or replacement of the gas valve or fan, as well as advanced diagnostics or repairs, must be carried out by a Gas Safe registered engineer.
How 0800 Homefix Can Help
We have extensive experience diagnosing and fixing Baxi E43 faults. Our expert service includes:
Testing and calibrating the gas valve and inspecting the gas supply valve for faults or calibration issues
Checking gas pressure, including for low gas pressure or too low gas pressure
Inspecting the ignition system and boiler ignition system, including the flame control sensor, flame sensor, and verifying the integrity of the flame signal
Repairing or replacing faulty fans and ensuring correct power supply
Checking the PCB and communication signals, as well as verifying controller parameters and supply voltage
Cleaning or replacing the air intake and flue components
Checking coolant temperature sensors and related diagnostics
Restoring safe and efficient boiler operation
We carry many manufacturer-approved spare parts to complete most repairs on the first visit.
Preventing Gas Valve or Fan Faults
Book an yearly boiler service to keep internal components clean and working correctly
Include annual sensor testing as part of regular servicing to ensure accurate detection and prevent sensor-related faults
Maintain the heating circuit by regularly checking for air in the system and inspecting the circulation pump’s electrical and mechanical parts for optimal performance
Keep external flue terminals free from obstruction
Listen for unusual fan noises and report them early
Use only qualified engineers for any maintenance or repairs
Note: Like other electronic mechanical devices and modern thermal equipment, Baxi boilers benefit from regular professional maintenance to ensure reliable operation and minimise malfunctions
FAQs
What does the E43 code mean on a Baxi boiler?
It indicates a fault with either the gas valve or the fan both essential for safe boiler operation.
Can I fix the Baxi E43 error myself?
No. These are gas and electrical components that require a certified Gas Safe engineer.
Note: For any serious boiler issues, always contact a qualified Gas Safe engineer to ensure safe and compliant repairs.
Is E43 dangerous?
Yes, as it relates to gas flow and combustion. The boiler shuts down to prevent further risk.
How quickly can 0800 Homefix fix it?
We aim to resolve most faults on the same day with OEM-compatible replacement parts.
FAQ
What is the role of the NTC temperature sensor, and what happens if the NTC sensor breaks? How do I check if the sensor is present?
The NTC temperature sensor monitors the boiler’s temperature to ensure safe operation. If the NTC sensor breaks, it can cause error codes like E50, leading to incorrect temperature readings and boiler shutdowns. To check if the sensor is present and functioning, a technician will inspect the wiring and test the sensor for continuity.
Why is maintaining the correct temperature range important, and what happens if the boiler operates outside a certain temperature range?
Boilers are designed to operate within a specific temperature range. Operating outside this certain temperature range can cause temperature failures or temperature defects, triggering error codes such as E25, E27, or E32. These issues may indicate rapid temperature changes or faults in the heating circuit, requiring system checks and maintenance.
What is the role of flue gases, flue gas control, and flue gas control systems in boiler safety?
Flue gases are the byproducts of combustion. Flue gas control and flue gas control systems monitor and regulate the temperature and flow of these gases to ensure safe operation. Malfunctions in these systems can trigger safety shutdowns and error codes, as proper flue gas management is critical for preventing hazardous conditions.
What does the traction sensor do, and how does it impact boiler operation?
The traction sensor monitors airflow and pressure within the boiler. Faults with the traction sensor, such as those indicated by error code E03, can affect the safety and efficiency of the boiler, sometimes causing it to shut down to prevent unsafe operation.
What is the DHW temperature sensor and its role in hot water regulation?
The DHW (domestic hot water) temperature sensor controls the temperature of the hot water supplied by the boiler. If this sensor fails, it can cause issues with hot water delivery and may trigger fault codes related to flame regulation or water temperature.
How are water pressure and central heating affected by error codes?
Low water pressure is a common cause of boiler malfunctions and can be indicated by specific fault codes. If water pressure drops, central heating and hot water may stop working. Restoring proper water pressure, checking for leaks, and topping up the system are common troubleshooting steps.
How do common Ariston boiler problems compare to Baxi boilers?
Common Ariston boiler problems include low water pressure (error code 108), PCB failures, and sensor faults. Like Baxi boilers, Ariston boilers can experience issues with temperature regulation, NTC sensors, and flue gas control. If you have an Ariston boiler or are comparing Ariston boilers to Baxi, both brands require prompt diagnosis and repair by a qualified Gas Safe engineer for persistent or complex faults.
If your Baxi boiler is showing the E43 fault, trust 0800 Homefix to provide expert diagnostics and safe repairs. Get your heating and hot water back without delay book a callout now.
Link to Baxi’s main support page