Ravenheat Fault Code 02 / E02 — Boiler Temperature Failure, Flue Obstruction or Pump Circulation Fault
Ravenheat uses slightly different code formats across its product range, so the exact display matters. The bare code '02' (no letter prefix) typically points to a boiler temperature failure or a flue/combustion air obstruction — the control board has detected that the fan has stopped or that the flue or air intake is blocked, and has shut down the burner as a safety measure. On some models such as the HE120 Low NOx condensing combi, this is specifically linked to what Ravenheat describes as anti-cycling of the flue evacuation system. The prefixed code 'E02' has a different meaning: it signals a pump circulation fault, where the internal pump is failing to move water adequately around the primary circuit, triggering overheat protection and halting operation to prevent heat exchanger damage.
General guidance only — not a substitute for professional advice. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
What does the Ravenheat 02 fault code mean?
Ravenheat uses slightly different code formats across its product range, so the exact display matters. The bare code '02' (no letter prefix) typically points to a boiler temperature failure or a flue/combustion air obstruction — the control board has detected that the fan has stopped or that the flue or air intake is blocked, and has shut down the burner as a safety measure. On some models such as the HE120 Low NOx condensing combi, this is specifically linked to what Ravenheat describes as anti-cycling of the flue evacuation system. The prefixed code 'E02' has a different meaning: it signals a pump circulation fault, where the internal pump is failing to move water adequately around the primary circuit, triggering overheat protection and halting operation to prevent heat exchanger damage.
Common causes
- Pump airlock (E02) Common
Air trapped inside the pump impeller prevents it from rotating freely, starving the circuit of adequate flow. This is particularly common after system maintenance, radiator work, or if the system pressure has been allowed to drop too low. Properties in hard-water areas or where radiators are rarely bled are especially prone.
- Pump shaft seized by sludge (E02) Common
Over time, corrosion debris and magnetite sludge from an untreated central heating system accumulates around the pump head and bearings. This gradually increases friction until the shaft seizes completely. Older Ravenheat system boilers such as the WH90 are frequently affected, particularly if the system has never been power-flushed or dosed with inhibitor.
- Flue or air intake obstruction (code 02) Common
A blocked flue terminal — caused by a bird nest, accumulated debris, or ice forming at the outlet in freezing weather — prevents safe evacuation of combustion gases. The control board detects the disruption and shuts the burner down. On some installations, a flue elbow that has dropped internally can also cause a partial obstruction.
- Pump motor electrical failure (E02) Sometimes
A failed capacitor in the pump motor, burnt windings, or a loose wiring connection can cause the pump to hum without spinning, or to stop entirely. The motor may appear to run intermittently before failing completely.
- Fan failure or air pressure switch fault (code 02) Sometimes
If the flue fan itself has failed mechanically or electrically, or if the air pressure switch that monitors fan operation has stuck or drifted out of calibration, the boiler will register the same temperature or flue obstruction-style lockout as a genuine blockage would cause.
- PCB fault Rare
In rare cases, the circuit board misreads signals from the pump, fan, or thermistors and generates a spurious fault code. This is more likely on older boilers where components have aged or where there has been a power surge.
How to fix it
- Check for an obvious flue blockage at the external terminal DIY safe
Go outside and visually inspect the flue outlet — usually a white plastic terminal on an exterior wall or the roof. Look for bird nests, leaves, ice build-up, or any debris covering the grille. If the terminal is iced over in cold weather, gently pour warm (not boiling) water over it to thaw it. Do not poke objects into the flue.
- Verify system pressure is within the normal operating range DIY safe
Check the pressure gauge on the boiler — it should read between 1.0 and 1.5 bar when the system is cold. If it is below 1 bar, top it up using the filling loop (a braided hose between two isolation valves, usually beneath the boiler). Open both valves slowly, watch the gauge rise, then close both valves once you reach 1.2–1.5 bar. Low pressure can contribute to poor pump performance and trigger an E02.
- Attempt a boiler reset DIY safe
Press and hold the reset button (or turn the dial to the reset position, depending on your model) for approximately three seconds, then release. Allow the boiler up to two minutes to restart. If the fault clears, monitor the boiler closely over the next hour. Do not reset more than two or three times in total — repeated resets without a successful restart indicate a genuine fault that needs investigation.
- Do not attempt to dismantle the pump or flue yourself Gas Safe engineer
Although some online guides suggest homeowners can bleed the pump or free a seized shaft with a screwdriver, doing so incorrectly risks flooding, introducing more air, or causing pump damage that turns a simple repair into an expensive one. Any internal work on the boiler — including accessing the pump, inspecting the fan, or testing the air pressure switch — must be carried out by a Gas Safe registered engineer.
- Call a Gas Safe registered engineer to diagnose and repair the fault Gas Safe engineer
A qualified engineer will carry out a systematic diagnosis: checking the pump for airlocks, seized bearings, or electrical faults; inspecting the fan and air pressure switch; confirming the flue is clear and correctly installed; and testing the PCB for any underlying component failures. For an E02 pump fault, they will bleed or replace the pump as required. For a code 02 flue fault, they will clear any obstruction and verify safe flue operation before returning the boiler to service.
Parts you may need
- Central heating circulating pump (replacement) · from £120
- Pump capacitor · from £8
- Flue terminal assembly · from £35
- Air pressure switch · from £45
- Flue fan motor · from £95
- Magnetic system filter (e.g. Magnaclean) · from £65
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £150–£380, depending on the underlying cause.
Frequently asked questions
What is the difference between fault code 02 and E02 on a Ravenheat boiler?
The two codes point to different problems. The bare '02' code relates to a boiler temperature failure or a flue/combustion air obstruction — the burner has shut down because the fan or flue system isn't working correctly. The 'E02' code (with the letter E) is a pump circulation fault, meaning the pump isn't moving water around the heating circuit properly. If you're unsure which code your boiler is displaying, check your model number and cross-reference it with your installation manual, or let a Gas Safe engineer confirm the diagnosis.
Can I fix a Ravenheat E02 pump fault myself?
There are a couple of safe things you can check first: make sure your system pressure is between 1.0 and 1.5 bar, and try resetting the boiler once or twice. Beyond that, the pump work itself — bleeding a pump airlock, freeing a seized shaft, or replacing the unit — should be done by a Gas Safe registered engineer. Accessing the pump incorrectly can cause water damage or introduce more air into the system, making the repair more expensive.
How much does it cost to fix a Ravenheat fault code 02 or E02 in the UK?
The most common repair — pump replacement — typically costs between £150 and £380 all-in, including parts and labour. A pump swap usually takes a Gas Safe engineer around two to three hours. Costs at the higher end are more typical in London and other cities. If the fault turns out to be caused by the fan or air pressure switch, you're likely looking at £100–£250. More complex issues such as a faulty PCB or gas valve can cost £400 or more in parts alone; on an older Ravenheat boiler, it's worth getting a replacement quote alongside any repair estimate.
Could a frozen flue cause a code 02 on my Ravenheat boiler?
Yes — in cold snaps, ice can form at the flue terminal and partially or fully block the outlet. The control board detects the disruption to combustion gas flow and shuts the burner down, which can register as a code 02. You can safely thaw a frozen flue terminal by pouring warm water over the external outlet. Once clear, reset the boiler. If the fault returns or the terminal keeps freezing, an engineer should review the flue installation — the terminal position or angle may need adjusting.