How Do I Reset My Furnace Ignitor

The furnace ignitor is a small but essential component that lights the burner in a gas furnace. Resetting it can solve many common heating problems without calling a technician. This article explains safe, step-by-step methods to reset an ignitor, how to diagnose related issues, and when to seek professional help.

Situation	Quick Action	Risk Level
Ignitor Not Glowing	Check power and gas, reset furnace power	Low
Clicking But No Flame	Inspect ignitor condition, replace if cracked	Medium
Furnace Shuts Down After Ignition	Clean flame sensor, check vents	Medium

How A Furnace Ignitor Works

The ignitor creates the heat or spark to light the furnace burner when the thermostat calls for heat. Modern furnaces typically use a hot surface ignitor (HSI) made of silicon carbide or silicon nitride that glows orange to ignite the gas. Some systems still use a spark ignitor or pilot assembly.

Key Point: If the ignitor fails to glow or spark, the furnace will not produce heat and may enter a lockout state after several failed attempts.

Safety Precautions Before Resetting

Always prioritize safety because gas and electricity are involved. Turn off power to the furnace at the service switch or circuit breaker before touching components. Avoid forcing parts, and never attempt repairs that expose gas lines or burners unless qualified.

• Turn off the thermostat and furnace power at the breaker.
• Allow components to cool to avoid burns.
• Disconnect gas only if instructed and comfortable; otherwise call a professional.

Tools And Materials Needed

Having the right tools makes the process quicker and safer. Basic items include a multimeter, insulated screwdrivers, a flashlight, soft brush, compressed air or canned air, and replacement ignitor if necessary. A camera or phone is useful to document wiring before disconnecting anything.

Initial Troubleshooting Steps

Before attempting a reset, perform these diagnostics to isolate the problem. These steps help determine whether a simple reset will work or if replacement is required.

1. Check thermostat settings and replace batteries if applicable.
2. Confirm furnace power switch and circuit breaker are on.
3. Inspect the furnace error code light; many units blink codes to indicate ignition faults.
4. Listen for the ignition sequence: inducer motor, gas valve click, ignitor glow or spark.

How To Reset A Furnace Ignitor: Step-By-Step

The following step-by-step method covers common household gas furnaces with hot surface ignitors. These steps are applicable to many models but always consult the furnace manual for model-specific instructions.

Step 1: Turn Off Power And Gas

Turn off the thermostat and locate the furnace power switch, often on or near the furnace cabinet. Flip the breaker to cut power. If the furnace has a gas shutoff near the unit, turn it to off for extra safety.

Step 2: Wait And Then Restore Power

Wait at least 30 seconds to 60 seconds to allow control boards and capacitors to reset. Restore power at the breaker and set the thermostat to call for heat. Some furnaces will clear minor electronic glitches simply by cycling power.

Step 3: Observe The Ignition Sequence

After restoring power, listen and watch the furnace sequence. The inducer motor should start, the gas valve should click, and the ignitor should glow or spark. If the ignitor still does not engage, proceed to inspection and testing steps.

Step 4: Inspect The Ignitor Visually

Open the furnace access panel and locate the ignitor near the burner assembly. Inspect for cracks, chips, or discoloration. A damaged ignitor cannot be reset and requires replacement. Handle ignitors carefully, as oils from fingers can shorten life.

Step 5: Test For Voltage With A Multimeter

With power restored and thermostat calling for heat, measure the voltage at the ignitor connector per the furnace wiring diagram. A hot surface ignitor typically receives line voltage pulse; a reading consistent with the manual indicates the control is firing the ignitor.

If the control supplies voltage but the ignitor does not glow, the ignitor is faulty.

Step 6: Check Furnace Error Codes And Reset Button

Many modern furnaces include a control board reset button or diagnostic LED. Follow the manufacturer’s reset procedure: typically press and hold the reset button, or cycle power three times within a specific interval. Consult the manual for exact sequences.

Cleaning And Maintaining The Flame Sensor

A common misdiagnosis is the flame sensor when the issue is ignition. However a dirty flame sensor can cause the furnace to shut off after ignition. Cleaning this component often restores reliable operation without replacing the ignitor.

1. Turn off power and open the access panel.
2. Locate the flame sensor near the burner and remove the screw holding it in place.
3. Gently clean with fine emery cloth or steel wool and wipe with a clean, dry cloth.
4. Reinstall and test the furnace.

When To Replace The Ignitor

Ignitors are fragile and suffer from thermal cycling fatigue. Replacement is required when the ignitor is cracked, does not glow under voltage, or fails intermittently after testing.

Replacement Indicators: visible damage, failed voltage test, frequent ignition lockouts, or repeated service calls for the same fault.

How To Replace A Hot Surface Ignitor

Replacing an HSI is a common homeowner task if comfortable with basic tools. Always power down the furnace and document wiring locations before removal.

1. Turn off power and gas to the furnace.
2. Remove the access panel and locate the ignitor assembly.
3. Disconnect the ignitor connector and remove mounting screws.
4. Install the new ignitor, avoiding touching its ceramic surface with bare hands.
5. Reconnect wiring, restore power, and test the furnace cycle.

Troubleshooting Chart: Ignition Problems And Likely Causes

Symptom	Likely Cause	Action
No Ignitor Glow	Failed ignitor, no control voltage	Test voltage; replace ignitor if voltage present
Ignitor Glows But No Flame	Gas valve failure, blocked gas line	Check gas supply, call technician for valve repair
Ignitor Clicks Then Lockout	Dirty flame sensor, airflow problems	Clean flame sensor, check filters and vents

Common Mistakes To Avoid

Rushing or skipping diagnostic steps can lead to unnecessary replacement costs or safety risks. Do not touch the ignitor element with bare hands, avoid using excessive force on panels, and never bypass safety devices.

• Do not assume power cycling always solves underlying issues.
• Do not use substitute parts; ensure OEM or compatible ignitor models.
• Avoid DIY gas valve or blower motor repairs unless certified.

When To Call A Professional

Contact a licensed HVAC technician for persistent ignition failures, suspected gas leaks, complex control board faults, or if uncomfortable performing electrical tests. Professionals can perform safe combustion analysis, gas pressure testing, and control board diagnostics.

Call a pro immediately if a gas odor is present or if repeated ignition attempts cause unusual noises or smells.

Extending Ignitor Life: Best Practices

Regular maintenance prolongs ignitor life and improves furnace reliability. Replace air filters, keep the furnace area clean, ensure adequate venting, and schedule annual professional inspections before the heating season.

• Replace filters every 1–3 months to reduce dust load.
• Keep burners and flame sensor clean during annual tune-ups.
• Ensure thermostat wiring and settings are correct.

Additional Resources And Manuals

Furnace model manuals, manufacturer troubleshooting guides, and HVAC forums provide model-specific advice. Reliable sources include manufacturer websites, the Air Conditioning Contractors of America (ACCA), and the U.S. Consumer Product Safety Commission for safety recalls.

For part numbers and wiring diagrams, locate the furnace nameplate and model number on the cabinet and reference the manufacturer’s online resources.

Summary Of Steps To Reset And Test An Ignitor

Resetting often involves cycling power and following a logical diagnostic process: ensure power and gas, cycle power, observe ignition sequence, visually inspect and test ignitor, clean flame sensor, and replace the ignitor if faulty. If safety concerns arise, consult a licensed technician.

Quick Reset Checklist	Action
Cut Power	Turn off breaker and wait 30–60 seconds
Restore Power	Turn breaker back on and call for heat
Inspect	Check ignitor for damage and test voltage
Maintain	Clean flame sensor and replace filters

Following these detailed steps helps diagnose and resolve most ignitor-related issues safely and effectively while reducing downtime and unnecessary service costs.