Furnace Igniter Glows But Burner Won't Light: Gas Valve, Flame Sensor, or Pressure?

Short answer: a glowing igniter proves only one step. After it, the gas valve has to open and the flame sensor has to prove a flame, or the control shuts the gas off. Goodman’s manual for its 80% single-stage furnaces lists a lockout after 3 tries. On 5 of our no-heat furnace calls in fall 2026, 2 were ignition faults. The other 3 never got that far.

So before anyone buys an igniter, it helps to know where the sequence stops. Below is what those 5 calls looked like, how a technician tells the causes apart, and what you can check first.

What we found on our fall 2026 no-heat furnace calls

Our CRM has 5 central gas furnaces with a no-heat call between September 29 and November 2, 2026 and a recorded cause. That took 7 visits, because two furnaces needed a second visit for the repair. None of these 7 jobs had the brand field filled in, so we searched job descriptions, technician notes and invoices for furnace and heater jobs. Floor furnaces, wall heaters and units with a standing pilot work differently, so they aren’t counted here. Older records imported from our previous system are too thin to search this way. It’s a small local sample.

Where those 5 were:

Only 2 of the 5 were ignition problems. On the other 3, the furnace never got as far as lighting: one had no power, one had a safety limit open, and one had a failed control board.

How to tell the causes apart

The order below follows the no-heat troubleshooting chart in Goodman’s service manual for its 80% single-stage furnaces (GM9S80, GC9S80 and related models). Other brands can differ. The steps and timings come from your model’s manual.

Nothing happens, and the light on the control board is off. The furnace has no power, or the control board has failed. Goodman’s chart lists a blown fuse or a tripped breaker for a board that shows no signal, and a control board that doesn’t work. Our Danville call was the no-power kind: the furnace wouldn’t turn on, and the fuse in the electrical disconnect on the wall had blown. After a new fuse it ran through several heating cycles with no faults. A fuse that blows again points to an electrical fault a technician should trace.

The furnace doesn’t start or blow air, and a limit has tripped. A safety limit opens when the furnace runs too hot or something else is wrong, and the control won’t light the burner while it’s open. Goodman’s chart sends a technician to blocked filters, restrictive ductwork and the blower when the primary limit is open and the blower keeps running. Our Fremont furnace didn’t blow air at all. A tripped limit was reset once and it ran, but the inducer motor hummed. We replaced both on a second visit.

The inducer runs, but the igniter never glows. The control checks the pressure switch before it powers the igniter. If the switch doesn’t close, Goodman’s chart has the technician check the draft the switch sees: too little points to the venting or a plugged pressure switch port, enough points to the switch itself. If the switch closes and the control sends power but the igniter still doesn’t glow, the chart says replace the igniter.

The igniter glows, but it goes dark early and the burner doesn’t light. Goodman’s chart expects the igniter to glow for the whole 17-second warm-up. If it stops early, the first thing to check is the pressure switch opening during warm-up.

The igniter glows for the full warm-up, but no gas lights. Now the chart moves to the gas valve: house gas pressure, then 24 volts at the valve, then the valve itself. Our Livermore call ended at the valve: the tenant reported only cold air. Gas pressure and control voltage were normal, but the valve didn’t open every time, so the furnace locked out.

The burner lights, then goes out after a few seconds. Gas keeps flowing only if the control senses a flame. Goodman’s manual says a nearly invisible coating on the flame sensor weakens that signal, and the chart lists a lockout after 3 ignition tries. Our older Fremont furnace, reported only as no heat, needed a new igniter, a cleaned flame sensor and adjusted pressure switches all at once.

What you can check first

Goodman’s no-heat chart and installation instructions cover the first three. The fourth is ours.

1. Check the furnace power switch and the breaker. The first box of Goodman’s no-heat chart asks whether both are on.
2. Check the thermostat. Make sure it’s set to heat. “Is thermostat properly set?” is in the same first box.
3. Check the filter. Switch the furnace power off before you pull the filter. Goodman’s installation instructions call a blocked or dirty filter one of the most common causes of a problem in a forced air heating system, and say to inspect filters monthly and replace them if needed. Measure the filter slot when you buy one. Our Danville furnace had the wrong size.
4. Write down what you see. Note whether the igniter glows, whether a flame appears and what the light on the control board is doing through the small window in the door, if your furnace has one. Don’t take a door off to look. Tell the technician.

Stop there. Don’t open the burner compartment, press reset buttons inside the furnace, or replace fuses in the wall disconnect. Goodman tells technicians to reset the auxiliary limit only once, “to avoid possible fire,” and to find out why before resetting it again.

If you smell gas, don’t light anything and don’t touch electrical switches. Leave the building and call the gas utility emergency line or 911 from a safe place. Goodman’s installation instructions give the same order: no flames, no switches, and call from a neighbor’s phone.

What we check

We follow the sequence from the thermostat call to the flame: power and the 24-volt signal from the thermostat, the inducer and pressure switch, the igniter through its full warm-up, the gas valve, then the flame signal. These are live gas and line-voltage tests, so they’re a technician’s job.

• Gas pressure at the inlet. We read it with a manometer. Goodman’s manual gives 4.5 to 10.0 inches of water column for natural gas. On our Livermore call it read 7.24 inches, with 27 volts of control voltage, both normal. That’s what pointed to the valve itself.
• Flame signal. It’s measured in microamps with a meter in series with the flame sensor wire. Goodman’s manual gives 1 to 4 microamps for its integrated ignition controls and lists a dirty sensor, a bad sensor-to-burner gap, poor grounding or high-resistance wiring when the reading is low.
• Why a limit opened. A limit that trips is a symptom. We look for the cause before calling it fixed.

What it costs

• Diagnostic visit: $99, credited toward the repair if you go ahead with us.
• A typical minor HVAC repair, such as an igniter: $250 to $650 for parts and labor. That’s the usual range for this kind of repair, not a quote for every furnace.

You get a written repair price to approve before any repair work starts. If the furnace is old enough that replacing it makes more sense, our guide on when to repair or replace a furnace covers that call. If the chart points at the pressure switch, see how a technician tests a furnace pressure switch.

When to call

Call (925) 999-4095 to schedule a visit.

Call when the furnace still won’t light after the checks above, when it lights and drops out, or when a breaker or fuse keeps going. Turn the thermostat off while you wait. Tell us the brand and model if you can see the label, and what the igniter and burner are doing.

We do furnace repair across the East Bay and Tri-Valley. These 5 calls were in Fremont, Livermore, Danville and Union City. We work on Goodman and York furnaces and other brands.

The diagnostic visit is $99, credited toward the repair. Call (925) 999-4095 or request a visit. We’re open 7 AM to 7 PM, 7 days a week.

Related service examples

• York gas furnace not turning on in Danville: blown disconnect fuse replaced
• York gas furnace flame sensor repair in Dublin

Key takeaways

• The igniter glowing is one step. Next the gas valve has to open and the flame sensor has to prove a flame, or the control shuts the gas off. Goodman's service manual for its 80% single-stage furnaces lists a lockout after 3 ignition tries.
• On 5 no-heat furnace calls in our records from late September to early November 2026, 2 were on the ignition side (a furnace that needed a new igniter, a cleaned flame sensor and adjusted pressure switches, and a gas valve that didn't open reliably). The other 3 were a tripped safety limit, a blown fuse and a failed control board.
• Before you call, Goodman's no-heat chart starts with the furnace power switch, the breaker and the thermostat setting. Check the filter too, with the furnace power off.
• Leave reset buttons, panels, gas valves and the flame sensor to a technician. If you smell gas, leave the building and call the gas utility emergency line or 911 from a safe place.

Related questions

Need help with your system? Call (925) 999-4095 or book a visit. Repair diagnostics are $99, credited toward the repair. Installation assessments are free.

Written by Andrew Kuznetsov. Andrew is the founder and owner of Bay Area HVAC Service (ADRIUM Service Solutions). He holds a California Contractor License (CSLB #1136642), EPA Section 608 Universal certification, and is factory-trained on Daikin (Houston, 2025) and Mitsubishi. He writes from direct field experience, not marketing copy.

Further reading

• Carrier Furnace Status Codes and Greenspeed Heat Pump Fault Codes , A Carrier furnace blinks a two-digit status code on an amber LED. A Greenspeed heat pump or AC sends a code like 18-11 to the Infinity thermostat. Here are both lists from Carrier's service manuals, by model, with the checks you can do before you call.
• Choosing a controller for your Mitsubishi system , Handheld remote, MHK2, wired control or the Comfort app: what to check before adding a controller to a Mitsubishi indoor unit.
• Mitsubishi heat pump lineup: which family fits your home? , Compare FX, GX, JX, HX and WX wall units, SUZ indoor styles and P-Series, then decide between a single-zone system and a multi-zone layout.