Error S.07

Safety precautions:

- If you smell gas, turn off the gas supply, leave the property immediately and call the gas emergency line. Do not try to diagnose the boiler.

- If there is visible water leaking from the boiler or large puddles, switch the boiler off at the mains and isolate the system at the filling loop if you can do so safely. Call an engineer.

- Do not remove the boiler casing or touch electrical terminals unless you are qualified. Live parts and gas components are dangerous.

Initial homeowner checks (safe, no covers removed):

1. Note when S.07 appears and whether it clears: run the heating or hot water, then turn it off and time how long the pump keeps running. If it clears within 5–10 minutes this is likely normal.

2. Check the programmer/timer and room thermostat settings: ensure the heating is actually switched off in the programmer and that a permanent override is not active.

3. Check room thermostat and TRVs: set the room thermostat higher than current room temperature to force a demand; then set it lower again to cancel demand and observe if the S.07 clears.

4. Look for other fault codes or warning lights, and check boiler pressure on the gauge (normal 1–2 bar when cold). Record any additional symptoms (noise, reduced hot water/heat, puddles, unusual smells).

5. Check for signs of water inside the boiler casing (corrosion, wet components) after a recent repair — report this to your engineer if found.

Simple diagnostic steps you can safely try:

1. Reset: use the boiler’s reset function once. If S.07 persists immediately after reset, stop resetting repeatedly and proceed to next checks.

2. Observe normal overrun: run hot water for a minute, then stop and see if the pump runs for ~5–10 minutes and the code disappears. If yes, no further action likely needed.

3. Test controls: temporarily cancel all heating demands at the programmer and room thermostat. If the pump continues running and S.07 stays displayed with no demand, this points to a control/wiring or pump fault.

4. Check for linked controls: if you have an external cylinder thermostat, room thermostat or zone valves, listen for zone valve motors or check their indicator positions (if accessible). A stuck or shorted valve motor can keep the boiler thinking there is a demand.

5. Observe pump behaviour: if you can hear or feel the pump but cannot access internals, note whether it is running continuously (even with all controls off). Continuous running usually means an electrical/control fault or mis-wired pump.

When to call a professional and what to tell them:

- Call a Gas Safe–registered engineer if S.07 does not clear within a few minutes, if it appears continuously, if you find water inside the casing, if other fault codes appear, or if you are uncomfortable performing the checks above.

- When you contact the engineer, provide: boiler model, exact fault code (S.07), whether it clears or is permanent, results of your timer/thermostat checks, any recent repairs or pump changes, and any signs of leaks or other faults.

Why a professional is likely needed:

- Persistent S.07 often requires testing or replacement of the pump, inspection and possible repair of wiring or the PCB, checking motorised zone valves, or addressing incorrect pump wiring after a replacement. These are gas and electrical safety tasks that must be done by a qualified engineer.

Notes and cautions:

- Do not repeatedly reset the boiler as a long-term fix; this can mask the underlying problem and may cause further wear.

- Avoid opening the boiler casing or trying to swap out electrical parts yourself — this can be dangerous and will almost certainly require a Gas Safe engineer for any gas-related or sealed-component work.

If the overrun is normal and clears within 5–10 minutes you can monitor it. If it is persistent, intermittent but frequent, or accompanied by leaks/other faults, book a Gas Safe engineer to diagnose and repair the pump, wiring, zone valves or control board.