

Baxi Boiler Error Codes
our team of heating engineers deliver excellent Baxi boiler services
With over 35 years of experience, our team of heating engineers deliver excellent Baxi boiler services.




















Baxi Boiler Error Codes
Derby's Local Heating Engineers
If your Baxi boiler has suddenly stopped working and is showing a fault code, it can be frustrating but these codes are actually designed to help you quickly identify what’s gone wrong. Each fault code corresponds to a specific issue, such as low water pressure, ignition problems, or temperature sensor faults.





Baxi Boiler Error Codes
On this page, you'll find a clear list of common Baxi fault codes and what they mean, so you can better understand the issue before calling an engineer.
Whether it’s a pressure problem, ignition failure, or sensor error, this guide will help you take the right next step, whether that’s a simple fix or getting in touch with us here at KCM Heating.
E Series Error Codes
E20 – Overheat or faulty sensor
Cause: The boiler has overheated or the temperature sensor is faulty.
Solution: Check the system for any blockages that may be restricting the flow of water. If the problem persists, the temperature sensor may need to be replaced by an engineer.
E28 – Flue thermistor fault
Cause: The flue thermistor has failed or is not functioning correctly.
Solution: The thermistor will need to be inspected and replaced if necessary. A professional engineer should handle this repair.
E50 – Hot water thermistor fault
Cause: The hot water thermistor has failed or is malfunctioning.
Solution: The hot water thermistor should be inspected and replaced if required by a qualified engineer.
E78 – Water pressure sensor fault
Cause: The water pressure sensor is not functioning correctly or is disconnected.
Solution: Check the water pressure gauge and top up the pressure if necessary. If the fault persists, the sensor may need replacing.
E1 Error Codes (Pressure & Sensor Issues)
E119 – Low water pressure (below 0.5 bar)
Cause: The system pressure is too low, typically below 0.5 bar.
Solution: Use the filling loop to increase the water pressure to around 1.0-1.5 bar. If the pressure keeps dropping, check for leaks in the system.
E133 – Ignition failure (gas supply issue or frozen condensate pipe)
Cause: The boiler has failed to ignite, possibly due to a gas supply issue, faulty ignition electrode, or a blocked condensate pipe.
Solution: Ensure the gas supply is turned on and the condensate pipe is not blocked (especially in cold weather). Reset the boiler and see if it ignites.
E168 – Power supply issue or system lockout
Cause: A problem with the power supply to the boiler or a faulty printed circuit board (PCB).
Solution: Check that the boiler is receiving power. If the issue persists, the PCB may need replacing by a professional.
E5 Error Codes (Fan & Airflow Issues)
E160 – Fan fault (possible fan failure or PCB issue)
Cause: The fan has failed or there is a blockage in the flue.
Solution: Check for any blockages around the flue or fan. If the fan is faulty, it will need to be replaced.
L Series Fault Codes (Lockouts & System Errors)
L1 – Overheat lockout
Cause: The boiler has overheated and locked out to prevent damage.
Solution: Reset the boiler. If it keeps locking out, check for any blockages or airlocks in the system that could be restricting water flow.
L2 – Ignition lockout (could be a gas supply issue)
L5 – System reset lockout (too many resets)
Cause: Too many unsuccessful reset attempts.
Solution: Wait for a few minutes before attempting to reset the boiler again. If the issue persists, contact an engineer to identify the underlying fault.

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