S.03 Medium
Your boiler is trying to start up to provide heating, but it keeps failing to light the flame correctly.
Technical description: Heating mode – ignition sequence error
Typical repair cost: £120-350 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Protect yourself from future repair bills
A boiler cover plan would cover faults like S.03 — no call-out fees, no surprises.
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Parts commonly replaced
- Ignition Electrode
- Spark Leads
- Gas Valve
- PCB
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