How to Fix Uneven Burner Firing on an LG Gas Stove

LG gas ranges feature UltraHeat burners capable of 22,000 BTU output for rapid boiling, along with standard and simmer burners across the cooktop. When these burners fire unevenly (flames higher on one side, yellow tips, flickering, or partial ignition around the burner ring), the cause is almost always a physical obstruction or misalignment rather than a gas supply problem. LG's sealed burner design means food spillovers cannot reach the gas orifice below, but they can clog the flame ports around the burner cap perimeter.

This guide addresses uneven firing on all LG gas range burner sizes, including the large UltraHeat burner where cap alignment is particularly critical due to the larger diameter and higher gas pressure. The procedures apply to LG ProBake Convection gas ranges, LG slide-in gas ranges, and LG freestanding gas stoves.

Before You Start

• Tools needed: Safety pin or sewing needle, soft toothbrush, damp cloth, flashlight, bowl of warm soapy water
• Parts needed: None (cleaning/adjustment procedure)
• Time required: 20-30 minutes
• Difficulty: Beginner
• Safety warning: Turn off all burner knobs to the OFF position. If you smell gas at any point during this procedure, do not proceed. Leave the area, ventilate, and call your gas utility emergency line. Do not use matches or lighters during cleaning. Allow burners to cool completely (30 minutes after last use) before handling.

Step-by-Step Instructions

Step 1: Remove the Grates and Burner Caps

Lift the cast iron grates off the cooktop and set them aside. Then lift each burner cap straight up. LG burner caps sit loosely on top of the burner base and are held in place only by gravity and alignment pins. The UltraHeat 22K BTU burner has the largest cap (approximately 5 inches diameter). Each cap has alignment notches on the bottom that must match the tabs on the burner base. Note which cap belongs to which burner, as LG uses different sizes for different positions.

Step 2: Inspect the Flame Ports

Examine the burner caps closely, looking at the small slots or holes around the outer perimeter. These are the flame ports where gas exits and ignites. Food debris, grease, and starch from cooking boil-overs accumulate in these ports, blocking gas flow and causing uneven flame distribution. On LG's UltraHeat burner, there are two rings of flame ports (inner and outer) that must both be clear for the full 22K BTU output.

Step 3: Clear Clogged Flame Ports

Use a safety pin or sewing needle to carefully push debris out of each clogged flame port. Insert the pin into the port opening and push outward (from inside the port toward the outside). Do not push debris further inward. Work around the entire circumference of each burner cap, clearing every port. For the UltraHeat burner with dual port rings, clear both the inner and outer rings. Count the ports as you go to ensure none are missed.

Step 4: Clean the Burner Caps

Soak the burner caps in warm soapy water for 10-15 minutes to dissolve grease buildup. Use a soft toothbrush to scrub around and inside each flame port after soaking. Rinse thoroughly under running water. Shake off excess water and dry completely with a clean cloth. Any moisture remaining in the flame ports will cause ignition problems. Allow caps to air-dry for 10 minutes after toweling to ensure complete dryness.

Step 5: Clean the Burner Base and Igniter

With the caps removed, clean the burner base (the fixed portion on the cooktop) with a damp cloth. Pay attention to the igniter electrode, which is the small white ceramic post with a metal tip near each burner base. Use a dry toothbrush to gently clean any carbon buildup from the igniter tip. Carbon deposits on the igniter increase the gap the spark must jump, causing clicking without ignition. Do not bend or reposition the igniter.

Step 6: Verify Burner Cap Alignment

Replace each dry burner cap onto its matching burner base. The alignment notches on the bottom of the cap must seat onto the corresponding tabs on the base. If the cap is rotated even slightly from its correct position, gas will escape unevenly from the ports and the flame will be asymmetric. On LG's UltraHeat burner, misalignment is the single most common cause of uneven high-output flame. Push the cap down gently and rotate it slightly until you feel the notches drop into the tabs. The cap should sit flat without rocking.

Step 7: Test Each Burner

Replace the grates. Turn one burner to the LITE position and verify the igniter clicks and the burner fires within 4 clicks (LG spec). Once lit, observe the flame pattern around the entire burner ring. Flames should be blue with consistent height around the perimeter. Slightly yellow tips are acceptable on the UltraHeat burner at maximum output. Repeat for each burner. If any burner still has uneven flames after cleaning, the burner base orifice may be partially blocked, which requires deeper access (see troubleshooting).

Step 8: Adjust Flame Height if Needed

If the flame height at the lowest setting (simmer) is too high or too low after cleaning, LG gas ranges have air shutter adjustments on the burner venturi tubes beneath the cooktop. Access these by lifting the cooktop panel (secured by clips on LG models, gently lift the front edge). The air shutter is a rotating band around the venturi tube entrance. Opening it more adds air (bluer, smaller flame). Closing it reduces air (larger, potentially yellower flame). Only adjust if flames are consistently yellow at all settings, indicating too-rich gas mixture.

Troubleshooting Common Issues

If cleaning and alignment do not resolve uneven flame on your LG gas stove:

• If one burner clicks continuously but will not ignite while others work fine, the spark igniter gap for that burner may have widened from thermal stress. The correct gap between the igniter tip and the burner grounding tab is 3-4mm on LG ranges. A wider gap requires higher voltage to spark across. Inspect with a flashlight and compare to working burners. Igniter replacement resolves this
• If all burners produce yellow, lazy flames even after cleaning, the gas pressure regulator may be delivering incorrect pressure. LG ranges require 4 inches WC for natural gas. This requires a manometer test by a gas technician. Do not attempt to adjust the gas regulator yourself
• If the UltraHeat burner fires normally on LOW but flutters or blows out on HIGH, the orifice for that burner may be partially restricted. The orifice is a brass fitting in the burner base that meters gas flow. Accessing it requires removing the burner base assembly. On ProBake models, this is accessible from below without lifting the cooktop on some configurations
• If you hear a popping sound when a burner ignites (delayed ignition), gas is accumulating before the spark fires. This indicates either a slow igniter (weak spark module) or partially blocked ports near the igniter position that prevent immediate flame propagation around the ring. Ensure the ports nearest the igniter electrode are perfectly clear
• Use LG ThinQ Smart Diagnosis (on connected models) to verify the control board is sending proper ignition signals. Smart Diagnosis can identify igniter circuit failures and gas valve control issues that are not visible during physical inspection

When to Call a Professional

Some gas stove issues require licensed gas technicians:

• If you smell gas with all burners OFF and the oven not in use, a gas leak exists in the supply line, shut-off valve, or internal manifold. Evacuate and call your gas utility emergency number immediately. Do not attempt to locate or repair gas leaks
• If the gas regulator needs adjustment (consistently yellow flames on all burners after cleaning), this requires a manometer and licensed gas technician. Incorrect gas pressure is dangerous and can produce carbon monoxide
• If burner orifices need replacement (incorrect size orifice installed during an LP/natural gas conversion), a technician must verify proper orifice sizing for your gas type and altitude
• If the electronic ignition module (spark generator) has failed (no clicking from any burner), the module replacement requires accessing the control panel area and verifying the high-voltage spark module output
• If the cooktop panel needs to be fully removed for deep cleaning beneath the burner assemblies, on some LG models this involves disconnecting gas connections that must be leak-tested upon reassembly

Cost Comparison: DIY vs Professional

Need Professional Help?

• stove repair service
• lg appliance repair
• stove repair cost guide

FAQ

Q: Why is my LG UltraHeat burner firing unevenly but the smaller burners are fine? A: The UltraHeat 22K BTU burner has a larger cap with more flame ports and tighter alignment requirements. Even slight cap misalignment on this burner causes visibly uneven flame due to the higher gas pressure. Remove the cap, verify the alignment notches seat fully into the base tabs, and ensure all ports in both the inner and outer flame rings are clear.

Q: Is it normal for LG gas stove flames to be slightly yellow at high heat? A: Small yellow tips on the UltraHeat burner at maximum output are acceptable and indicate the burner is approaching its maximum gas/air mixture ratio. However, fully yellow or orange flames at any setting indicate insufficient air in the mixture and require air shutter adjustment or port cleaning.

Q: How often should I clean LG gas stove burner caps? A: Monthly cleaning prevents buildup that causes uneven firing. If you cook frequently with high-boilover foods (pasta, soups), clean weekly. The UltraHeat burner accumulates debris faster due to its use for high-heat boiling where spillovers are most common.

Q: Can I put LG burner caps in the dishwasher? A: LG does not recommend dishwasher cleaning for burner caps. The harsh detergents and high heat can damage the matte enamel finish on the caps. Hand washing in warm soapy water with a soft brush is the recommended method.

---

Need a certified technician? Book same-day repair →