Ravenheat Boiler Error Codes, Meaning, Causes & How To Fix

Ravenheat Boiler Error Codes: Full Guide to Causes and Fixes 2026

Quick Answer: Ravenheat uses different fault code systems across their model ranges — the CSI 120, CS 80/90 and WH ranges, and the HE range each display codes differently. The most common faults are ignition failure (code 01), low water pressure (E08/08E), and overheat sensor activation (E09/09E). Low pressure codes can be resolved by repressurising the system. All other Ravenheat fault codes require a Gas Safe registered engineer to diagnose and repair.

Ravenheat Manufacturing Ltd is a UK boiler manufacturer based in Leeds with a long track record in the residential heating market. Their product range includes the CSI 120, CS 80/90, WH System, WH 80/90, and the HE series — and each range uses a slightly different fault code format. This guide covers every Ravenheat error code across all model ranges in a clear reference format alongside detailed explanations for the most commonly reported faults.

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How Ravenheat Fault Codes Work Across Different Models

Ravenheat uses three distinct code formats depending on the boiler model installed. The CSI 120 uses plain numeric codes such as 01, 02, and 04. The CS 80/90, WH System, and WH 80/90 use E-prefix codes such as E02, E08, and E09. The HE 80/90, HE 25-30s, HE 80-98s, and HE 25-30s Compact use E-suffix codes such as 02E, 08E, and 09E. There is also a general F-prefix code range that applies across certain Ravenheat models for sensor and component faults. Identifying which model is installed is the essential first step before looking up a code.

Common Ravenheat Boiler Error Codes

Code 01 / E08 / 08E — Ignition Failure and Low Pressure

Code 01 — Ignition Failure (CSI 120)

Code 01 on the Ravenheat CSI 120 indicates a problem with the ignition system — the boiler has attempted to light the burner and failed. This results in no hot water or heating until the fault is resolved. There are five possible causes: a faulty burner unit, a damaged electrode, a damaged ignition lead, a problem with the spark generator, or a fault within the PCB. All five require a Gas Safe engineer to diagnose and repair — none can be resolved by the homeowner.

Checking that the gas supply is active by confirming other gas appliances in the property are working normally is a practical first step before calling an engineer. If the gas supply is confirmed and a single reset does not clear the code, a Gas Safe engineer should be called.

Can you fix it yourself? Check gas supply and attempt one reset. Call a Gas Safe engineer if code 01 persists.

E08 / 08E — Water Pressure Too Low (CS and HE Ranges)

The E08 and 08E codes — appearing on the CS 80/90 and WH range and the HE range respectively — both indicate the system water pressure has dropped too low for safe boiler operation. This is the most straightforward Ravenheat fault and the only one most homeowners can resolve without a Gas Safe engineer.

Adding water to the system via the filling loop to restore pressure to the manufacturer’s recommended level will clear E08 and 08E in most cases. If pressure drops again shortly after being restored, a slow leak is present in the system and a Gas Safe engineer should locate and repair it.

Can you fix it yourself? Yes — repressurise via the filling loop to the recommended level. Call an engineer if pressure drops repeatedly.

Code 28 / F83 — Low Water Levels

The code 28 on the CSI 120 and F83 on other models both indicate dangerously low water levels within the boiler. This is a safety-critical fault. When water levels drop below the minimum, heating surfaces can overheat severely. If cold water is then reintroduced rapidly, it converts to steam and can expand to over 1,500 times its volume — creating a serious risk of pipe rupture if there is insufficient space for expansion in the system. Homeowners must also consider the potential costs associated with repairs caused by these safety issues, which can be significant. To mitigate financial strain, exploring boiler financing options for homeowners can provide flexible payment plans that ease upfront expenses. Additionally, selecting the right financing option can help homeowners maintain a safe and efficient heating system without compromising their budget.

Because of the safety implications, this fault must be attended to by a Gas Safe registered engineer. The boiler should not be restarted or any water added by the homeowner without professional guidance on the specific cause of the low water level.

Can you fix it yourself? No — a Gas Safe engineer is required immediately.

Code 09E / E09 — Overheat Sensor Overheating

The 09E and E09 codes indicate the boiler’s overheat sensor has been triggered. This happens when the boiler overheats — most commonly because a safety feature protecting the system from overtemperature has failed to operate correctly, allowing temperatures to rise beyond safe limits. The boiler enters lockout mode when this code appears to prevent operation in a potentially unsafe condition.

A Gas Safe engineer must establish the cause of the overheating event before the lockout is reset. Continuing to reset an overheating boiler without identifying the cause risks progressive heat exchanger damage that is expensive to repair.

Can you fix it yourself? No — a Gas Safe engineer is required before any reset.

Full Ravenheat Error Code Reference: General F-Codes

Full Ravenheat Error Code Reference: CSI 120

Full Ravenheat Error Code Reference: CS 80/90, WH System, WH 80/90

Full Ravenheat Error Code Reference: HE 80/90, HE 25-30s, HE 80-98s, HE 25-30s Compact

Fault Code Detail: Key Secondary Codes

E02 / 02E — Pump Circulation Fault

These codes indicate the boiler’s circulation pump is not moving water around the heating circuit as expected. The pump may have seized, partially failed, or the system may have an airlock preventing circulation. A Gas Safe engineer should inspect the pump and heating circuit before recommending pump replacement, as an airlock can produce the same symptom as a pump failure and is a less expensive fix. In cases where the issue persists, warmflow boiler error code solutions may provide insight into additional troubleshooting steps. Understanding the specific error codes displayed can help narrow down potential problems and ensure a quicker resolution. Proper maintenance and regular servicing can also prevent many common issues associated with boiler performance.

E05 / 05E — Fan Fault and Code 17 — Fan Voltage Fault

These codes indicate a problem with the combustion fan — E05 and 05E covering a general fan fault and code 17 on the CSI 120 indicating specifically a fan voltage issue. The fan controls combustion air supply and flue gas exhaust, and a fault preventing correct fan operation causes the boiler to shut down for safety. Fan motor failure, a wiring fault, or a faulty fan control board are the most common causes, all requiring a Gas Safe engineer.

E06 / 06E — Central Heating Sensor Overheating

These codes indicate the central heating temperature sensor has detected an overtemperature condition. This is most commonly caused by poor water circulation — a failing pump, closed radiator valves, or an airlock — preventing heat from being dissipated through the radiator circuit. A Gas Safe engineer should assess the full heating circuit before the lockout is reset.

E25 / 25E — Frozen Main Heat Exchanger

These codes indicate the main heat exchanger has frozen, most likely due to the condensate pipe becoming blocked with ice during cold weather. Thawing the condensate pipe by pouring warm water gently along its external length may resolve E25 and 25E without an engineer’s visit if freezing is the confirmed cause. Once thawed, a reset should restore normal operation. If the code persists after thawing, or if temperatures have not been below freezing, a Gas Safe engineer should investigate.

Can you fix it yourself? Thaw the condensate pipe if below-freezing conditions are the likely cause. Call a Gas Safe engineer if the fault persists.

E31 / 31E — OpenTherm Communication Fault

These codes indicate a communication failure between the boiler and a connected OpenTherm-compatible control device such as a smart thermostat. Checking that the external control device has power — including replacing batteries on wireless models — is a practical first step. If the control has power and the communication fault persists, a Gas Safe engineer should inspect the wiring between the thermostat and boiler.

E41 / 41E and F84 — Flow and Return Temperature Difference

These codes indicate an abnormal temperature difference between the flow and return pipes, which typically points to a circulation problem preventing heat from being transferred effectively through the heating circuit. Poor pump operation, a blockage, or a heat exchanger fouled with sludge are the most common causes. A Gas Safe engineer should inspect the full heating circuit and pump before recommending specific component replacement.

Code 30 and 31 (CSI 120) — Flue Temperature Failures

These codes on the CSI 120 indicate the flue temperature has exceeded safe parameters on two different thermostat points. Excessive flue temperatures can indicate heat exchanger problems, incomplete combustion, or a flue obstruction. The boiler should not be restarted until a Gas Safe engineer has confirmed the cause. Understanding the implications of boiler flue regulations in the UK is essential for maintaining safety and compliance. Regular inspections and adherence to these regulations can help prevent dangerous situations and ensure that equipment operates efficiently. Additionally, staying informed about any updates to these regulations will help in making timely adjustments to maintenance practices.

FAQ

How do I know which Ravenheat fault code system applies to my boiler?

The fault code format displayed on the control panel identifies which system your Ravenheat boiler uses. Plain numeric codes (01, 02, 28) indicate a CSI 120. E-prefix codes (E02, E08, E09) indicate a CS 80/90, WH System, or WH 80/90 model. E-suffix codes (02E, 08E, 09E) indicate a HE series model. The boiler model number is printed on a label inside the boiler casing or on the front panel and should be checked if the code format is unclear.

Can I fix Ravenheat boiler faults myself?

E08 and 08E low pressure codes can be resolved by the homeowner by repressurising the system via the filling loop. E25 and 25E frozen heat exchanger codes can often be resolved by thawing the condensate pipe with warm water during cold weather. E10 and 10E high pressure codes may be improved by bleeding a radiator. Checking the gas supply and attempting one reset is appropriate for code 01 before calling an engineer. All other Ravenheat fault codes require a Gas Safe registered engineer.

What does Ravenheat code 28 mean?

Ravenheat code 28 on the CSI 120 — equivalent to F83 on other models — indicates dangerously low water levels within the boiler. This is a safety-critical fault requiring immediate attention from a Gas Safe engineer. When water levels are critically low, heating surfaces can overheat severely, and introducing cold water can create a rapid steam expansion that risks pipe rupture. The boiler should not be restarted or water added by the homeowner without professional guidance.

What does the Ravenheat 09E or E09 code mean?

The Ravenheat 09E and E09 codes indicate the boiler’s overheat sensor has been triggered, causing the boiler to enter lockout mode. This happens when temperatures within the boiler have risen to a level that triggered the overheat protection system. The most common underlying causes are poor water circulation from a failing pump, a closed radiator valve, or a very low system pressure. A Gas Safe engineer must identify and resolve the cause of the overheating before the lockout is reset, as repeatedly resetting an overheating boiler risks progressive heat exchanger damage.

What should I do if my Ravenheat boiler shows ERR?

The ERR code indicates a fault with the boiler’s user interface — the control panel display and input buttons. This is an electronic fault that requires a Gas Safe engineer with Ravenheat product experience to diagnose. The interface component may need repair or replacement. If the display is the only affected function and the boiler is still providing heat and hot water, the fault is less urgent, but it should still be investigated by an engineer as it may indicate a broader control board issue developing.

When should I replace a Ravenheat boiler rather than repair it?

Ravenheat is a smaller UK manufacturer than brands such as Viessmann or Worcester Bosch, and parts availability for older models should be confirmed before committing to a major repair. For a Ravenheat boiler under 10 years old with a single straightforward fault, repair is almost always worth pursuing. For boilers over 10 to 12 years old where multiple faults are recurring, or where major components such as the PCB, heat exchanger, or gas valve motor require replacement, a new A-rated boiler installation is likely to deliver better long-term reliability and lower running costs. A Gas Safe engineer can give an honest assessment of whether repair is viable given the boiler’s age and parts availability.

Conclusion

Ravenheat’s multi-range fault code system is more complex than most single-range boiler brands, but once the correct model range is identified the codes provide clear and consistent fault information across the CSI 120, CS/WH, and HE series. Of all the codes covered in this guide, E08 and 08E low pressure are the only faults most homeowners can resolve independently by repressurising the system. E25 and 25E frozen heat exchanger faults can sometimes be cleared by thawing the condensate pipe during cold weather. The safety-critical code 28 and F83 low water level codes require immediate professional attention and should not be reset by the homeowner.

Annual servicing by a Gas Safe registered engineer remains the most effective way to prevent Ravenheat fault codes, keep the boiler operating safely and efficiently, and extend the operational lifespan of the system throughout its expected 10 to 15-year service life.