Troubleshooting Gas Fireplaces That Won’t Turn On

A gas fireplace that won’t turn on is not a single problem. It’s a symptom.

Unlike wood fireplaces, gas units depend on multiple interdependent systems:

• Gas supply and pressure
• Ignition method (Standing Pilot, IPI, or Millivolt)
• Safety sensors (thermocouples, thermopiles, flame rods)
• Electrical or millivolt power generation
• Airflow and venting conditions
• Control logic (boards, switches, remotes)

When any one of these systems fails—or sends the wrong signal—the fireplace will not ignite, or will shut itself down intentionally.

This guide walks through every major failure path, in the correct diagnostic order, so you can determine why your indoor gas fireplace won’t turn on—not just guess.

Step One: Identify What “Won’t Turn On” Actually Means

Before touching anything, clarify the failure behavior. A fireplace that “won’t turn on” usually falls into one of these specific categories:

• Nothing happens at all (dead silence)
• Pilot won’t light
• Pilot lights but main burner doesn’t
• Fireplace turns on briefly, then shuts off (short cycling)
• Clicks repeatedly but never ignites (spark no flame)
• Worked before, stopped suddenly
• Only fails during cold weather
• Only fails during power outages

Each behavior points to a different subsystem. Never troubleshoot blindly.

Step Two: Confirm the Ignition System Type

You cannot troubleshoot correctly until you know how the fireplace is designed to ignite. Indoor gas fireplaces generally use one of three ignition architectures. (See our guide on Ignition Types for visual identification).

1. Standing Pilot System

• Constant pilot flame burns 24/7.
• Uses a thermocouple or thermopile.
• Often works without electricity.
• Common in older units and simpler stoves.

2. Intermittent Pilot Ignition (IPI)

• Pilot lights only when heat is called for.
• Controlled electronically by a module.
• Requires household power or battery backup.
• Common in modern high-efficiency units like the Empire Rushmore series.

3. Millivolt System

• Pilot generates its own electrical voltage via a thermopile.
• No external power required for the burner.
• Often uses a wall switch or simple remote.
• Popular for reliability and outage operation.

Step Three: Check Gas Supply (Before Anything Else)

No gas equals no fire. This sounds obvious, but it’s the most overlooked step in field diagnostics.

Verify the Gas Shutoff Valves

Check the appliance shutoff valve (usually in the control cavity or floor) and the main household gas shutoff. Valves must be fully parallel to the pipe. A half-open valve can cause a "lazy" pilot flame that is too weak to generate the millivolts needed to open the main valve.

Confirm Other Gas Appliances Work

Turn on a stove burner or check the water heater. If multiple appliances fail, the issue is upstream—at the meter or utility—not the fireplace.

Gas Pressure Problems

Low gas pressure causes weak pilot flames, delayed ignition, and burner dropout. Pressure issues may come from regulator failure, frozen gas lines (common with propane), or undersized piping.

Step Four: Pilot Will Not Light

This is one of the most common complaints. The diagnosis depends on the system type.

For Standing Pilot Systems

If the pilot won’t light at all:

• Air in the line: Common after summer shutdown. Hold the pilot knob for 60+ seconds to bleed air.
• Clogged Pilot Orifice: Spiders love the smell of mercaptan in gas. Spider webs in gas burners and pilot tubes can block flow entirely, requiring compressed air cleaning.
• Faulty Piezo Igniter: If the sparker doesn't click, you may need to light it manually with a match to test gas flow.

A healthy pilot flame should be mostly blue, wrap around the thermocouple tip, and remain stable. Yellow or flickering flames indicate contamination or draft issues. For detailed steps, refer to pilot light troubleshooting guides.

For IPI Systems

If the pilot won’t light but you hear clicking:

• Check for dead batteries in the backup pack.
• Inspect for a cracked ignition wire (spark arcing to chassis instead of pilot).
• Verify the control module is grounded.

If there is no clicking at all, check the power source, blown fuses, or loose wiring at the wall switch.

Step Five: Pilot Lights but Main Burner Won’t

This is a classic safety lockout scenario. The system sees a pilot, but refuses to open the main gas valve because it cannot prove the flame is safe.

Thermocouple or Thermopile Failure (Millivolt/Standing Pilot)

The pilot flame heats the sensor to generate voltage. If the pilot lights but the valve won't open, the sensor isn't sending the "open" signal.

• Thermocouples: Generate ~30mV. If the tip is burned or the connection is loose, the valve closes.
• Thermopiles: Generate 300-750mV to power the main valve. You can use a multimeter to check output. See this guide on how to test a thermopile correctly.

Heat equals signal. No heat signal equals no gas flow.

Gas Valve Failure

The gas valve is the gatekeeper. If it doesn’t receive the correct voltage or millivolt signal, it remains closed. Diagnosing this requires a multimeter to troubleshoot the millivolt gas valve solenoid terminals. If voltage is present but the valve won't open, the valve operator is likely seized.

Step Six: Fireplace Turns On Then Shuts Off

This usually indicates a safety system doing its job. The unit lights, detects a dangerous condition, and cuts fuel.

Flame Sensor Issues (IPI Systems)

Modern systems use flame rectification. The control board sends an electrical signal through the flame to the ground rod. If the sensor is dirty (coated in white silica or soot), the signal is blocked.

Understanding flame rectification basics is critical here: the flame acts as a conductor. Cleaning the sensor rod with a dollar bill or fine steel wool often resolves this immediately.

Overheat or Limit Switch Triggers

Fireplaces include temperature limits (snap discs). Shutdown occurs if:

• Airflow is blocked (blower fan failure).
• Venting is restricted.
• Mantel clearances are violated.

Draft or Venting Problems

Poor draft causes flame rollout or exhaust recirculation. If the system detects heat spilling out of the firebox (spill switch), it shuts down to prevent carbon monoxide risk.

Step Seven: Fireplace Won’t Turn On During Power Outage

This depends entirely on the ignition type. (Read our Power Outage Guide for more).

• Standing Pilot / Millivolt: Should operate normally without power. If not, the thermopile output may be too weak to drive the valve without the help of the grid-powered fan or accessories.
• IPI Systems: Require electricity or a battery backup. Dead backup batteries are the #1 cause of outage failure in modern units.

Step Eight: Wall Switches, Remotes, and Controls

Controls fail more often than fireplaces.

Wall Switch Issues

Standard toggle switches wear out. A simple bypass test involves removing the switch cover and touching the two wires together. If the fireplace ignites, the switch is bad.

Remote Control Problems

Common failures include dead receiver batteries (inside the hearth), lost pairing (needs re-syncing), or RF interference from other devices.

Step Nine: Safety Lockouts and Error Codes

Modern IPI fireplaces include timed lockouts. If the unit fails to light after 3 attempts, it enters a "hard lockout" to prevent gas buildup. This requires a manual reset (usually turning the power switch OFF for 5 seconds, then ON).

Step Ten: Environmental and Seasonal Causes

Gas fireplaces can fail seasonally.

• Cold Weather: Propane pressure drops in extreme cold, and condensation can freeze in vent caps.
• Summer Inactivity: Insects clog pilot tubes, and dust accumulates on sensors. Annual maintenance is key.

Step Eleven: DIY vs Professional Boundaries

You can safely:

• Check gas valves and shutoffs.
• Replace batteries in remotes and receivers.
• Clean flame sensors and glass.
• Verify switch wiring.

You should NOT:

• Adjust gas pressure regulators.
• Modify venting configurations.
• Bypass safety switches.
• Replace gas valves without leak testing.

When Replacement Is the Real Answer

Sometimes the fireplace isn’t “broken” — it’s obsolete. Indicators include discontinued parts, repeated valve failures, unsafe venting design, or outdated safety standards. In those cases, replacement is safer than repair.

Summary: Diagnose, Don’t Guess

When a gas fireplace won’t turn on, the system is either missing fuel, missing power, missing a signal, or intentionally protecting itself. The key is systematic elimination, not trial and error.

Need Help Diagnosing a Gas Fireplace That Won’t Turn On?

If you’re stuck mid-diagnosis, unsure whether the issue is electrical, gas-related, or safety-triggered, we can help you think through the next step before costly mistakes.

📧 support@pureflameco.com
📞 +1-833-922-6460

Next Best Article in This Series:
Gas Fireplace Ignition Types Explained: Pilot, IPI & Millivolt Systems