Intergas 0 Fault Code: Causes, Fixes & Repair Costs
What does the Intergas 0 fault code mean?
Fault code 0, which may appear as 0.0 or 0.00 depending on your Intergas model, indicates that the system water pressure has dropped below the acceptable minimum threshold. The boiler's PCB has detected insufficient pressure in the central heating circuit and has locked the boiler out as a precaution. Without adequate pressure — typically between 1 and 1.5 bar — the boiler cannot circulate water safely, which risks damaging the heat exchanger, pump, and other internal components. Check the pressure gauge on the front of the boiler: a reading below 0.5 bar almost certainly confirms low pressure as the root cause, though a persistent or recurring drop may point to a leak or a failing component rather than simple pressure loss.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. 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.
Common causes
- Low system pressure following normal use or radiator bleeding Common
Central heating systems naturally lose a small amount of pressure over time. Bleeding radiators also releases water along with trapped air, causing a noticeable pressure drop. If the gauge reads below 1 bar and you have recently bled radiators or not topped up the system for a long time, this is the most straightforward explanation.
- Leak in the pipework, radiators, or towel rails Common
Even a slow, minor leak somewhere in the system can cause repeated pressure loss. Check visible pipework under the boiler, around radiator valves, and at towel rail connections for signs of moisture, rust staining, or limescale deposits — all of which can indicate a weeping joint or pinhole leak.
- Internal boiler leak from degraded pump seals Sometimes
The circulating pump contains seals that deteriorate with age. Once they begin to fail, the pump can leak internally, draining pressure from within the boiler casing where it may not be immediately visible. Older Intergas units can suffer water damage to surrounding components as a result of even small pump seal leaks.
- Faulty or weeping pressure relief valve (PRV) Sometimes
The PRV is designed to release water if pressure becomes dangerously high, but if it has started to weep or fail it can discharge small amounts of water continuously. Check whether the overflow pipe outside the property is dripping — a clear sign the PRV needs attention.
- PCB fault or water damage to the PCB Rare
If an internal leak has been present for some time, water may have reached the PCB and caused damage. A damaged PCB can also misreport the fault code, meaning the displayed code may not accurately reflect the underlying problem. This is usually confirmed or ruled out by an engineer using a multimeter to test individual connections.
How to fix it
- Check the pressure gauge reading DIY safe
Locate the pressure gauge on your Intergas boiler — it is usually visible on the front panel or through a viewing window. A healthy reading is between 1.0 and 1.5 bar. If the needle sits below 0.5 bar, low pressure is the confirmed trigger for fault code 0. Note the reading before doing anything else.
- Repressurise the system using the filling loop DIY safe
Find the filling loop — typically a short braided hose with one or two valves located beneath or near the boiler. Slowly open the valve(s) to allow mains water into the system, watching the pressure gauge rise. Stop when it reaches around 1.2–1.3 bar. Close the valve(s) fully. Do not overfill beyond 1.5 bar. If you are unsure where the filling loop is, consult your Intergas user manual or a short manufacturer video guide.
- Bleed the radiators DIY safe
After topping up pressure, bleed all radiators starting on the ground floor and working upwards. Use a radiator bleed key to open the bleed valve slightly until air hisses out, then close it once water appears. This removes trapped air that can cause circulation problems. Check the pressure gauge again after bleeding and top up slightly if it has dropped.
- Reset the boiler DIY safe
Once pressure is back in the correct range, reset the boiler using the reset button (refer to your model's user guide for the exact location). Allow the boiler to restart and monitor it for several minutes. Limit resets to two or three attempts — repeated resetting without resolving the root cause risks further damage.
- Inspect for visible leaks DIY safe
If the pressure drops again within a few hours or days, look carefully at all visible pipework, under the boiler, around radiator valves, and at towel rail connections for any sign of dampness, rust marks, or mineral deposits. Do not ignore even small damp patches. If you find evidence of a leak, do not repressurise again — call an engineer.
- Call a Gas Safe registered engineer to investigate further Gas Safe engineer
If the pressure continues to drop after repressurising, if you cannot locate the filling loop, if you suspect an internal leak, or if the boiler trips out repeatedly, you need a Gas Safe registered engineer. They will pressure-test the system to locate hidden leaks, inspect the pump seals and PRV, and test the PCB with a multimeter to rule out electrical faults or water damage. Continuing to run the boiler with unresolved low pressure risks serious and costly damage to the heat exchanger and pump.
Parts you may need
- Circulating pump (Intergas compatible) · from £120
- Pump seal kit · from £25
- Pressure relief valve (PRV) · from £35
- Filling loop assembly · from £20
- Pressure gauge · from £30
- PCB (Intergas model-specific) · from £220
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 £90–£320, depending on the underlying cause.
Frequently asked questions
Why does my Intergas boiler keep losing pressure even after I top it up?
Recurring pressure loss almost always means water is escaping the system somewhere. The most common culprits are a weeping radiator valve, a leaking pipe joint, or a pressure relief valve that is slowly discharging water through the overflow pipe outside. A Gas Safe engineer can carry out a pressure test to find hidden leaks that are not immediately obvious. In older boilers, degraded pump seals are also worth investigating. Repeatedly topping up without fixing the root cause is not a safe long-term solution.
What pressure should my Intergas boiler run at?
Intergas recommends a cold system pressure of around 1.0 to 1.5 bar, with 1.2 to 1.3 bar being the sweet spot most engineers aim for. When the heating is running and the water is hot, pressure naturally rises slightly — typically to around 1.5 to 2.0 bar — which is normal. If it climbs above 2.5 bar or drops below 0.5 bar, the boiler will lock out to protect itself.
Could a PCB fault be causing the fault code 0 on my Intergas boiler?
It is possible, though relatively uncommon. The PCB monitors all sensor data including the pressure sensor reading. If the PCB itself has been damaged — often by water ingress from an internal leak — it may display an incorrect fault code or fail to read the pressure accurately. An engineer can test each PCB connection with a multimeter to confirm whether the board is the source of the problem. PCB replacement on Intergas boilers typically costs around £250 to £400 including labour, which is why engineers will rule out all simpler causes first.
Is it safe to keep resetting my Intergas boiler when fault code 0 appears?
You can try a reset once or twice after topping up the pressure to see whether the boiler fires up normally. However, if fault code 0 keeps returning, continuing to reset without investigating the cause is not advisable. Operating the boiler with persistently low pressure puts unnecessary strain on the heat exchanger and circulating pump — two of the most expensive components to replace. Get the system checked by a Gas Safe engineer if the fault reappears after two or three resets.