Written by Stephen Day
Gas Safe Engineer
Updated: 30th May, 2025
Error codes can range from ignition troubles to pressure fluctuations, each denoting a specific set of underlying issues.
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Ravenheat boiler systems serve as critical components in many UK homes, providing warmth and hot water with notable efficiency.
However, like any sophisticated mechanical system, these boilers can present error codes signalling various faults that may disrupt their operation.
These error codes are not merely random numbers or characters; they are integral to diagnosing the exact nature of a problem and are the first step in the troubleshooting process.
Homeowners and engineers rely on understanding these codes to swiftly and effectively restore boiler functionality, maintaining the comfort and safety of the household.
Error codes can range from ignition troubles to pressure fluctuations, each denoting a specific set of underlying issues.
It is important to note that while some error codes may indicate simple issues that can be resolved without professional intervention, others may require the expertise of a Gas Safe registered engineer.
Moreover, the process of resolving these errors varies in complexity and might entail resetting the boiler, cleaning essential components, or replacing faulty parts.
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While some error codes are straightforward enough to be identified and fixed by homeowners, we always advise contacting a Gas Safe engineer to assess the situation and carry out any repairs necessary.
All of iHeat’s engineers are fully qualified and Gas Safe, ensuring a swift and safe installation.
17 - Fan Voltage Issue: Indicates a problem with the voltage supply to the fan.
01 - Boiler Ignition Faulty: This code signals an issue with the boiler's ignition system.
28 - Low Water Levels: Suggests that the water level in the boiler is lower than required.
12 - Heating Sensor Faulty: Indicates a malfunction in the heating sensor.
04 - Failure Due to Overheating: The boiler has overheated, causing a system failure.
30 & 31 - Flue Temperature Failure: These codes indicate an issue with the temperature in the flue system.
02 - Boiler Temperature Failure: Points to a problem with the overall temperature of the boiler.
E02 - Pump Circulation Fault: There's an issue with the circulation in the pump.
E03 - Damaged Flow Sensor: Indicates that the flow sensor has been damaged.
E04 - Hot Water Sensor Damaged: The sensor responsible for detecting hot water temperature is damaged.
E05 - Faulty Fan: Points to a problem with the boiler's fan.
E06 - Central Heating Sensor Overheating: The central heating sensor is overheating.
E08 - Pressure Too Low: The pressure in the system is lower than it should be.
E09 - Overheat Sensor Overheating: The sensor detecting overheating is itself overheating.
E10 - Boiler Water Pressure Too High: The pressure within the boiler is excessively high.
E13 - Software Error: Indicates a problem within the boiler's software.
E21 - Central Heating Return Sensor Overheating: The return sensor in the central heating is overheating.
E22 & E23 - Overheating/ Faulty Flue Sensor: Issues related to the flue sensor, either overheating or malfunctioning.
E24 - Heating Return Sensor Fault: Problem with the sensor in the heating return circuit.
E25 - Frozen Main Heat Exchanger: The main heat exchanger in the boiler has frozen.
E29 - Hot Water System Overheating: The system responsible for heating water is overheating.
E31 - Comms Problem with OpenTherm: Communication issues with the OpenTherm system.
E41 - Flow and Return Temperature Difference: The temperatures of the flow and return are different than expected.
E42/E43/E44 - Different Temperature Points Issue: Problems with temperature at various points in the system.
E46 - Water Pressure Sensor Problem: The sensor detecting water pressure is experiencing issues.
02E to 10E: These codes are similar to the Ravenheat CS 80/90, WH System, WH 80/90 error codes, representing issues from pump circulation problems to high water pressure.
13E to 46E: These codes also mirror the issues found in the CS 80/90, WH System, WH 80/90 models, including software problems, temperature differentials, and water pressure sensor issues.
F73 & F74 - Pressure Sensor Fault in Heating Circuit: Both codes indicate issues with the pressure sensor in the heating circuit.
F76 - Faulty Thermal Fuse: The thermal fuse in the boiler has become faulty.
F77 - Faulty Gas Valve Motor: There's a malfunction in the motor of the gas valve.
F83 - Lack of Water in the System: The system is lacking sufficient water.
F84 - Flow and Return Heating Sensors Have Different Temperatures: The temperatures sensed by the flow and return sensors differ significantly.
F85 - Faulty Flow and Return Heating Sensors: Both the flow and return heating sensors are faulty.
F86 - Fault with the Underfloor Heating Contact: There's an issue with the contact for underfloor heating.
ERR - Faulty User Interface: The user interface of the boiler is experiencing a fault.
04 - Faulty Hot Water Sensor: The sensor responsible for detecting hot water temperature is faulty.
Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.
Effectively, New boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer.
Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.
Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).
Installation Type | Price (inc VAT) | |
Combi to combi swap | £1,845 | |
System to combi conversion | £2,499 | |
New boiler install | £2,899 | |
Back boiler to a combi | £3,299 | |
System to system | £1,945 |
Last updated: 30th May, 2025
Written by Stephen Day
Gas Safe Engineer at iHeat
Stephen Day is a Gas Safe registered and FGAS certified engineer with over 20 years of hands-on experience in the heating, cooling, and renewable energy industry, specialising in boiler installations, air conditioning, and heat pump systems.
LinkedInArticles by Stephen Day are reviewed by iHeat’s technical team to ensure accuracy and reliability.
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