Absolute Gas Burner Won't Stay Lit When You Let Go of the Knob?
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You push the knob in, the burner lights, and the moment you let go the flame dies. It's one of the most common gas hob faults we fix, and in most cases the cause is a small safety part called the thermocouple.
🔍 R350 call-out to inspect & diagnose · waived if we do the job⚡ Same-day call-outs · 90% of major spares carriedQuick answer
If a gas burner lights but goes out as soon as you release the knob, the flame-safety device, called the thermocouple, isn't holding the gas valve open. Hold the knob in for 10 to 15 seconds after lighting, make sure the burner cap is seated properly, and clean the thermocouple tip. If it still goes out, the thermocouple or its valve needs replacing. Never bypass it. Absolute Repairs replaces thermocouples on Smeg, Bosch, Defy and other gas hobs across Gauteng for a R350 call-out, which is waived if we do the repair.
What a thermocouple does
Every burner on a modern gas hob has a flame-failure safety device. Its job is simple and important: if the flame goes out, it shuts off the gas so your kitchen doesn't fill with unburnt gas.
The thermocouple is a thin metal probe that sits right next to the burner, in the flame. When the tip is heated, it produces a tiny electrical current. That current powers a small magnet in the gas valve behind the knob, which holds the valve open. When you push the knob in, you're holding the valve open by hand until the thermocouple warms up and takes over. If the thermocouple can't produce enough current, the magnet lets go the moment you release the knob, and the gas cuts off.
Need it fixed?
Our technicians come to you anywhere in Gauteng. The call-out is a flat R350 to diagnose the fault (waived if you go ahead with the repair), you get a fixed price before any work starts, and every repair has a 6-month guarantee.
Try these checks first
- Hold the knob in longer. After the burner lights, keep the knob pressed for a full 10 to 15 seconds before letting go. A thermocouple needs time to heat up, especially when it's getting older.
- Check the burner cap. If the cap or the flame spreader is not seated properly, the flame may not touch the thermocouple tip. Lift it off and put it back so it sits flat.
- Clean the tip. With the hob cold, gently clean the thermocouple tip with a dry toothbrush or fine scourer to remove burnt-on grease and boil-over residue. Keep it dry.
- Look at its position. The tip should sit where the flame touches it. If it has been knocked sideways during cleaning, the flame misses it.
- Check other burners. If all burners go out, the problem may be the gas supply, such as an almost-empty LPG cylinder or a faulty regulator, rather than every thermocouple at once.
When it needs replacing
If one burner still won't stay lit after those checks, the thermocouple has usually worn out, or its connection at the gas valve has corroded or come loose. Less often, the magnet unit in the valve itself has failed. On many cookers, the hob has to be lifted to reach them, which is a job for a qualified technician.
A real repair: Smeg cooker in Waterkloof
On a recent job in Waterkloof, a Smeg 90 cm dual-fuel cooker had exactly this fault. The burners lit, but the flames died as soon as the customer let go of the knob. We lifted the hob, tested the flame-safety system, replaced the faulty thermocouple and tested every burner. They all stayed lit. See more Smeg repairs.
Safety first
- Never bypass or wedge a thermocouple. It's the only thing stopping gas from flowing when a flame blows out.
- If you smell gas, turn off the burner and the cylinder valve or gas supply, open windows and doors, and don't switch lights or appliances on or off until the smell has cleared.
- Don't keep holding the knob for minutes trying to make it work. If it doesn't stay lit after 15 seconds, stop and have it checked.
Other gas hob problems
If the igniter clicks non-stop, it's often moisture or a faulty spark switch. If you get a shock when lighting, read our gas stove electric shock guide. For electric ovens and plates, see oven and stove repair.
The same repair, done by our team elsewhere in Gauteng
Frequently asked questions
Why does my gas burner go out when I let go of the knob?
The thermocouple (flame-safety device) isn't holding the gas valve open. It may be dirty, out of position, worn out, or loosely connected to the valve. Hold the knob in for 10 to 15 seconds and check the burner cap first. If it still goes out, the thermocouple needs replacing.
How long should I hold the gas knob in?
About 10 to 15 seconds after the burner lights. That gives the thermocouple time to heat up and hold the valve open on its own.
Can I bypass the thermocouple on my gas stove?
No. The thermocouple shuts off the gas if the flame goes out. Bypassing it can let unburnt gas fill your kitchen. A faulty one should be replaced.
Is a thermocouple expensive to replace?
It's usually an affordable part. The cost depends on the cooker brand and how much needs to be dismantled. We charge a flat R350 call-out and give you a fixed price before any work starts.
Why do all my gas burners keep going out?
If every burner goes out, check the gas supply first. An almost-empty LPG cylinder or a faulty regulator can lower the pressure. A single burner going out is usually its thermocouple.
Need it fixed?
Send us the brand, model and what it's doing on WhatsApp. Monday to Saturday, 07:30–17:30.
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- Genuine OEM parts fitted wherever they're available, and we tell you upfront if we use a quality equivalent
- Technicians with over 10 years of experience and 10,000+ completed jobs
- 6-month guarantee on every repair and installation
- Flat R350 diagnostic call-out anywhere in Gauteng, waived if you go ahead with the repair
- Fixed price agreed before any repair work starts
- Same-day call-outs, and we carry around 90% of major spares
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