Pilot Light Keeps Going Out: Causes & Solutions

Quick Answer: Pilot lights go out due to thermocouple failure (most common), dirty pilot assembly, draft issues, or low gas pressure. Some fixes are DIY, but most need a Gas Safe engineer.

Common Causes

1. Faulty Thermocouple

Most common cause

The thermocouple is a safety device that:

• Senses if pilot is lit
• Keeps gas valve open
• Shuts gas off if flame goes out

When it fails, it thinks there's no flame and cuts the gas.

Fix: Replace thermocouple (£65-£120 including labour)

2. Dirty Pilot Assembly

Buildup on the pilot jet can:

• Reduce flame size
• Prevent proper thermocouple heating
• Cause inconsistent lighting

Fix: Clean or replace pilot assembly (£50-£100)

3. Draft Issues

Strong drafts near boiler can blow out pilot:

• Damaged flue
• Poor ventilation
• Nearby windows/doors

Fix: Check flue integrity, seal drafts (£50-£150)

4. Low Gas Pressure

If gas pressure is too low:

• Pilot flame will be weak
• May not heat thermocouple enough
• Other gas appliances also affected?

Fix: Gas supply issue - call supplier or engineer

Can I Relight It Myself?

Older boilers (with standing pilot): Yes, follow boiler manual:

1. Turn gas to pilot position
2. Hold down button/dial while lighting
3. Continue holding 30-60 seconds
4. Release and turn to "On"

Modern boilers (electronic ignition): Usually self-relight. If not lighting:

• Check for error codes
• Try resetting
• Call engineer if continues

When It's Dangerous

Call Gas Emergency (0800 111 999) if:

• You smell gas
• Pilot lights but flame is yellow/orange (should be blue)
• Soot or black marks around burner
• Carbon monoxide detector activated

Cost of Repairs

Repair	Cost
Thermocouple replacement	£65-£120
Pilot assembly clean	£50-£80
Pilot assembly replace	£80-£150
Gas valve repair	£150-£300

Note: If boiler is old (15+ years), consider replacement vs repair.

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Gas Safe engineer Glasgow: +44 141 468 9930