Intergas 29 Fault Code: Causes, Fixes & Repair Costs
What does the Intergas 29 fault code mean?
Fault code 29 on an Intergas boiler indicates that the control system has detected a problem with the gas valve relay. The gas valve is the component responsible for regulating the flow of gas to the burner and pilot light — when the relay that controls it malfunctions, the boiler cannot safely manage gas flow and will lock out as a precaution. You will have no heating or hot water until a Gas Safe registered engineer has diagnosed and resolved the issue. On some Intergas Combi Compact models, code 29 is grouped with code 30, both pointing to the same gas valve relay fault. Note: a small number of informal online sources associate code 29 with low water pressure or ignition problems, but Intergas's own documentation consistently identifies this code as a gas valve relay fault — that is the authoritative interpretation.
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
- Faulty gas valve relay Common
The relay is the electrical switching component within the gas valve assembly that opens and closes the valve on demand from the PCB. When the relay fails — either due to wear, heat damage, or internal electrical failure — the boiler's control board detects the fault and triggers code 29. This is the most common root cause and often means the gas valve needs replacing entirely.
- Wiring or electrical connection fault Sometimes
Poor or corroded connections between the PCB and the gas valve can disrupt the electrical signal, causing the boiler to report a valve relay fault even if the valve itself is functional. An engineer can use a multimeter to confirm whether the valve is actually receiving a 230V supply and check for any damaged wiring or loose terminals.
- Faulty PCB (printed circuit board) Rare
If the PCB is generating intermittent or incorrect output signals, it may falsely trigger fault code 29 or be unable to operate the gas valve relay correctly. Engineers typically rule out the valve and wiring first before concluding the PCB is at fault, as PCB replacement is more costly.
How to fix it
- Check the rest of your gas supply is working DIY safe
Before assuming a boiler fault, confirm that other gas appliances in your home (such as a hob or gas fire) are working normally. If none of your gas appliances have a supply, contact your gas network operator — the fault may be with the supply rather than the boiler.
- Attempt a single boiler reset DIY safe
Locate the reset button on your Intergas boiler (usually a button or a symbol on the control panel — consult your user guide if unsure). Press and hold it as instructed. If the boiler fires up and runs normally, monitor it over the next hour. If fault code 29 returns promptly, do not keep resetting — repeated resets on a gas valve fault will not fix the underlying problem and may indicate a safety risk.
- Do not attempt any further DIY investigation Gas Safe engineer
Fault code 29 involves the gas valve — a safety-critical gas component. Inspecting, testing, or adjusting gas valves, relays, or associated wiring is work that must only be carried out by a Gas Safe registered engineer. Attempting this yourself is both dangerous and illegal under UK gas safety regulations.
- Book a Gas Safe registered engineer to inspect the boiler Gas Safe engineer
The engineer will carry out electrical safety checks (short circuits, earthing), verify the boiler is receiving the correct 230V supply, and confirm the gas inlet pressure at the valve is approximately 20 mbar. They will use a multimeter to test whether the gas valve relay is receiving power and functioning correctly.
- Engineer to repair or replace the gas valve Gas Safe engineer
If the relay or valve is confirmed faulty, the engineer will repair it where possible or fit a replacement gas valve. Where the valve is physically jammed and cannot be fully freed, or where an electrical fault makes repair impractical, a new valve will need to be installed.
- Engineer to test and replace the PCB if required Gas Safe engineer
If the gas valve and wiring check out as serviceable but the fault persists, the engineer will investigate the PCB. If it is producing intermittent signals or has sustained damage, it will need to be replaced before the boiler can operate safely.
- Reset the boiler after the repair is complete DIY safe
Once the engineer has completed the repair and confirmed the boiler is safe, they will reset the appliance to clear fault code 29 from the display. The boiler should then restart and operate normally. If the code reappears shortly after, let the engineer know immediately.
Parts you may need
- Gas valve assembly (Intergas compatible) · from £150
- PCB (printed circuit board) · from £250
- Gas valve wiring loom / harness · from £30
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 £250–£450, depending on the underlying cause.
Frequently asked questions
Is Intergas fault code 29 dangerous?
Yes, it has the potential to be. The gas valve controls all gas flow to the burner, and a faulty relay means the boiler cannot reliably manage that flow. Intergas boilers lock out when this fault appears precisely because continued operation would be unsafe. Do not attempt to override the lockout or repeatedly reset the boiler — get a Gas Safe engineer to inspect it promptly.
Can I fix Intergas fault code 29 myself?
No. This fault involves a gas component — the gas valve and its relay — which may only be worked on by a Gas Safe registered engineer under UK law. The only steps a homeowner can safely take are checking their wider gas supply is on and attempting a single reset. Everything else must be left to a qualified professional.
How much does it cost to fix Intergas fault code 29 in the UK?
For most households, the repair involves either replacing the gas valve or resolving a wiring fault, which typically costs between £250 and £450 including parts and labour. If the PCB turns out to be the root cause, replacement costs tend to be higher — often in the region of £400–£500 or more depending on the model. If your boiler is older and facing multiple expensive repairs, it may be worth asking your engineer whether a new boiler is more cost-effective.
What is the difference between Intergas fault codes 29 and 30?
On many Intergas Combi Compact models, codes 29 and 30 are closely related and both point to a gas valve relay fault. Some manufacturer documentation groups them together under the same diagnosis. In practice, engineers treat both codes the same way — by testing the gas valve relay, associated wiring, and PCB. If your display shows either code, the same course of action applies: call a Gas Safe registered engineer.