Troubleshooting Furnace Pilot Light Problems

If your pilot light won’t stay lit, it usually points to a handful of safety or combustion parts that work together to keep a steady flame. The thermocouple tells the gas valve the pilot is hot, the pilot orifice meters the fuel, and outside factors like drafts or low gas pressure can interrupt the flame. Persistent outages show consistent symptoms — the pilot lights but dies, the flame is weak, or the main burners won’t fire — and fixing the failing part or condition restores normal operation. Below we list common causes and a short checklist so you can match what you see to likely problems before taking action. These quick checks can cut unnecessary calls while keeping safety first; the next sections explain how to verify each possibility safely.

Follow the manufacturer’s procedure, but here’s the common sequence for most standing-pilot millivolt systems. Set the gas control to OFF and wait 5–10 minutes to let any gas disperse. Turn the control to PILOT, press and hold the pilot button, then apply your ignition source. Keep holding the pilot button for the manufacturer’s recommended time — usually 30–60 seconds — so the thermocouple heats up, then release. If the pilot stays lit, turn the control to ON and watch for the main burners to come on when the thermostat calls. If the pilot won’t stay lit after several careful attempts, or if the flame is yellow and sputtery, stop and move to the troubleshooting steps for thermocouple or orifice issues. Taking each step slowly and waiting the suggested times helps the thermocouple register enough heat and prevents dangerous premature gas flow.

After relighting, watch the flame for steady color and shape; the next section explains what to look for and when to clean or call a professional.

Spotting pilot light trouble usually comes down to flame color and stability plus how the furnace performs. A healthy pilot flame is steady and blue, centered on the thermocouple; changes in color or behavior suggest incomplete combustion, contamination, or supply trouble. Operational signs include no heat, short cycling, or main burners that don’t ignite. Safety signs include a gas smell or carbon monoxide alarm — either of those needs immediate action. Below are practical visual and operational clues and a short table to help you decide the right response.

If the pilot fails, the main burners may not ignite and the furnace will produce no heat. If there’s no smell of gas, this is usually an isolated pilot or control issue you can investigate with safe relight and diagnostic checks. If you smell gas, do not attempt to relight — shut off the gas at the appliance or meter only if it’s safe to do so, evacuate, and call emergency services or your gas provider from a safe location. Knowing the difference between no-heat/no-smell and no-heat/with-smell situations helps you take the right, timely action to protect people and property.

Troubleshooting combines careful observation, safe cleaning, and simple tests so you can often fix small problems without special tools. Focus on isolating thermocouple faults, clearing orifice clogs, and ruling out gas-valve problems with methodical checks: clean visible debris, test thermocouple response, and retest after each step. Start with visual cleaning and relighting; then move to multimeter checks or parts replacement if needed. Always follow safety rules — don’t relight if you smell gas or a CO alarm is active. The next sections explain how to clean or test a thermocouple and how to address a clogged pilot or suspected gas-valve problem, plus clear boundaries for when to hire a certified technician.

A clogged pilot orifice restricts gas and causes a weak, yellow, or extinguishing flame. You can sometimes clear it carefully with compressed air or a very small-gauge wire following the furnace manual. Only disassemble as much as the manual allows and avoid damaging the orifice or seals — if you’re unsure, stop and call a pro. Gas-valve problems and low gas pressure are more serious: if multiple appliances are affected or the pilot won’t stay lit after proper cleaning and checks, do not attempt valve work yourself. A certified technician should perform gas-valve diagnostics, pressure testing, and repairs to ensure safe fuel handling.

Before moving on: use the escalation summary below to decide when to call a professional, and review local-service options if you need help.

Use these decision triggers to protect your household and avoid risky DIY escalation. The next section explains specific safety risks that demand expert attention and then shows local service options.

Comfort Air Conditioning & Heating offers residential furnace diagnostics, repair, and maintenance across San Diego and nearby communities. Our technicians perform on-site thermocouple testing, pilot-orifice cleaning, gas-valve checks, and combustion safety inspections, and we’ll recommend repair or replacement when parts are worn. We serve San Diego, Poway, Escondido, Santee, Chula Vista and surrounding areas, and we provide clear quotes and scheduling to move from diagnosis to repair quickly. If you encounter a safety trigger like a gas smell, CO alarm, or repeated relight failure, contact a local qualified HVAC provider right away — we’re here to help restore safe, reliable heat.

Knowing how your pilot light works and how to safely troubleshoot it gives you more control over your home’s heating and safety. Follow the steps here for basic relighting and cleaning, and call a licensed HVAC technician whenever you hit a safety trigger or the problem persists. Regular maintenance and timely repairs keep your furnace working efficiently and safely all season. If you’d like help,reach out to Comfort AC & Heating to get your system inspected and running reliably.