Why Is My Gas Hob or Oven Flame Yellow? Causes and Fixes

A yellow flame means the gas isn't burning completely because it isn't mixing with enough air. The usual causes are burner ports blocked with grease or dust, a burner head that isn't seated properly, an air shutter that needs adjusting, or the wrong gas pressure from a faulty regulator. A yellow flame blackens pans, gives less heat and can raise carbon monoxide in the kitchen, so it needs cleaning, adjusting and good ventilation. Small orange flecks that come and go in an otherwise blue flame are usually just dust burning off and nothing to worry about.

The colour of a gas flame isn't just about looks. It is the quickest way to tell whether your oven or hob is working properly. A healthy flame is blue and steady, with a lighter blue inner cone. It doesn't roar and doesn't leave soot. The more the flame turns yellow or orange, the less efficiently it is burning.

Why is a flame blue in the first place?

Before gas leaves the burner ports, it passes through a short tube with an opening that draws in air from around it. There the gas mixes with air, and the mix burns completely, giving a hot blue flame. If less air gets into the mix, part of the gas burns incompletely, and the unburnt carbon particles glow yellow. Those same particles are the black soot you see on the bottom of your pans.

Common causes of a yellow flame

Yellow flames at altitude

In cities high above sea level, such as Taif and Khamis Mushait, there is less oxygen in the air, so the flame can come out longer and less steady if the air shutter is left on factory settings. Setting the shutter for local conditions brings back a short blue flame. See our Taif and Khamis Mushait pages for more.

Is a yellow flame dangerous?

Incomplete burning produces more carbon monoxide, a gas with no colour and no smell. In a well-aired kitchen with short use you may not notice anything, but in a closed kitchen with long use, especially with the oven, it can cause headaches and dizziness. That is why a yellow flame shouldn't be left unfixed, and why you should always run the extractor or open a window while cooking.

If you or anyone at home feels a headache, dizziness or nausea while the oven is on, switch it off at once, open the windows and go outside for fresh air. Have the oven checked before using it again.

What you can do yourself

1. Turn off the burner and let it cool completely.
2. Lift off the burner cap and head and look at the ports. If they are clogged with grease, soak them in warm soapy water.
3. Clear the ports with a soft brush or a thin non-metal pin if you can, without widening them.
4. Dry them fully, then put the head and cap back so they sit exactly in place.
5. Light the burner and look at the flame. If it is blue again, you are done.

Don't use a wooden toothpick or an iron nail to clear the ports. Wood can snap inside the port, and iron can widen it so the flame shape changes for good.

If the yellow flame is in the oven's own burner rather than the hob, it is harder to reach and usually means taking out the oven floor. A technician handles that as part of gas oven cleaning.

When do you need a technician?

• The flame is still yellow after cleaning the burner heads.
• Every burner and the oven are yellow at once, which points to the pressure, regulator or jets.
• The flame jumps high or roars.
• The yellow flame is in the oven's inner burner.
• You smell gas or an unusual burning smell.

The technician checks the pressure, sets the air shutter, confirms the jet sizes, then tests each burner one by one. For hobs, see what the service covers on our gas hob and burner repair page.

Yellow, orange or red: what's the difference?

People often ask about one exact colour, and the answer is that they all point to the same thing in different amounts. Small orange flecks that come and go in a blue flame are usually dust or salt from food burning off, and are normal. Steady yellow tips on a blue flame mean a little too little air, and cleaning is usually enough. A flame that is fully yellow or orange, long and dancing, means clearly incomplete burning that needs checking. A dark red flame with smoke is rare and means a big mixing problem, so switch the cooker off and call a technician.

How to keep the flame blue

• Wipe spills around the burner once it is cool, before they bake on.
• Soak the burner heads and caps every couple of weeks, depending on use.
• Don't put very large pots on a small burner, as they trap the air around the flame.
• Check the regulator and hose regularly. See when to change them in when to replace your gas hose and regulator.
• Deep clean the oven and hob about every six months.

Read the flame: length, sound and steadiness

Colour isn't the only sign. Watch three other things too. Length: a healthy flame is short and crisp, about the same size from every port, while a long dancing flame means too little air. Sound: a soft hiss is normal, but a loud roar, or a pop when you turn it off, means too much air in the mix or pressure that is too high. Steadiness: a flame that lifts off the burner as if floating away, or one that flashes back and burns inside the tube, both need adjusting by a technician.

Take a photo or short video of the flame before you call a technician. It helps him judge the problem before the visit, and you can send it straight over WhatsApp.

Common questions