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burner Issue

Flame Failure Lockout Issues

Repeated flame failures indicate a real problem—find the root cause.

Emergency: (877) 489-3727Start Diagnosis

What You're Experiencing

The burner ignites but then shuts down on flame failure, entering a safety lockout state. The flame may extinguish immediately after proving, or it may run...

Visual Signs:

  • Flame failure fault code on burner controller
  • Lockout LED illuminated
  • Flame visible initially then extinguishes
  • Erratic or unstable flame appearance
  • Flame lifting off burner or appearing yellow/lazy

Sound Signs:

  • Burner starts then suddenly stops
  • Audible click of gas valve closing on lockout
  • Alarm buzzer indicating lockout condition
  • Flame sounds rough or pulsating before failure

Safety Risks — Read Before Proceeding

high(NFPA 86 Section 8.6)

Repeated ignition cycles increasing flashback risk

Action: Stop attempting restarts. Diagnose the root cause before any further operation.

high(OSHA 1910.252)

Incomplete combustion producing CO

Action: Unstable flames may produce carbon monoxide. Ensure area is ventilated.

medium

Production delays

Action: Do not paint below minimum temperature. Schedule urgent repair.

Immediate Steps to Take

  1. 1

    Note the specific fault code displayed on the controller

  2. 2

    Do not repeatedly reset without diagnosis

  3. 3

    Check combustion air supply and filter condition

  4. 4

    Verify gas supply pressure is stable

  5. 5

    Inspect flame through sight glass when it is lit—is it stable and blue?

  6. 6

    Check for obvious burner contamination or damage

  7. 7

    Call for professional service if issue persists after one reset

Common Causes

Here are the most likely reasons you're experiencing this problem, ranked by how often we see them.

Dirty Flame Sensor

common

The flame rod has carbon buildup or oxidation that prevents it from properly sensing the flame. This is the #1 cause of flame failure lockouts.

Flame Sensor Positioning

common

The flame sensor has shifted position and is not in the proper flame envelope. It may be sensing intermittently.

Combustion Air Problems

occasional

Insufficient or unstable combustion air supply is causing flame instability. Dirty filters, blocked intake, or wind effects.

Gas Pressure Fluctuations

occasional

Gas supply pressure is varying during operation, causing flame instability or extinguishment. Regulator issues or undersized supply.

Burner Fouling

occasional

The burner head, orifices, or air mixer are fouled with debris or corrosion, causing poor flame quality.

Flame Signal Circuit Issue

rare

Wiring, grounding, or control board issue affecting flame signal transmission even when flame is present.

Interactive Diagnostic Tool

Flame Failure Diagnostic

Step 1 of 5

Does the flame ignite but extinguish within seconds?

If unsafe at any point: If flame appears dangerously unstable, yellow, or you smell uncombusted gas, shut off the burner immediately and call WERCS at (877) 489-3727.

When to Call WERCS

While some issues can be resolved with basic troubleshooting, these situations require professional service:

  • Flame failure occurs more than once
  • Flame sensor needs cleaning (not user-serviceable)
  • Flame appears unstable, yellow, or lifting
  • Gas pressure seems inconsistent
  • Reset only provides temporary relief
  • Production is halted due to heating failure

Priority Service Available

(877) 489-3727

Expert technicians nationwide

Flame Failure Lockout Issues FAQ

Common questions about this issue

The most common cause is a dirty flame sensor—these should be cleaned annually. Other causes include gas pressure drops, combustion air issues, improper flame sensor positioning, or electrical/wiring problems. A professional can quickly diagnose the specific cause.
Flame sensor cleaning requires shutting down the burner, accessing the combustion chamber, and using specific techniques to avoid damaging the sensor. While some facilities have trained staff who can do this, most call for professional service to ensure proper cleaning and system verification.
Flame failure at high fire often indicates insufficient gas supply pressure. At high fire, the burner demands more gas. If the supply line, regulator, or meter is undersized, pressure drops below what the burner needs, causing flame instability or failure.
Flame sensors (rods) can last 5-10 years with proper maintenance, but they need annual cleaning. The ceramic insulator can crack from thermal cycling, and the rod itself oxidizes over time. Replace proactively if showing wear during annual inspection.

Have a question not answered here?

Call us at (877) 489-3727

Related Problems

Burner Not IgnitingBurner CyclingGas Valve Problems

Related Parts & Components

Flame SensorGas ValveBurner Controller

Can't Fix It? We Can.

WERCS expert technicians service paint booths and extraction systems nationwide. 24/7 emergency service available.

Call (877) 489-3727Request Service Quote