Would you know if your car was overheating before it’s too late? The warning light many motorists don’t recognize – and what to do when it happens
- Motorists confused about ‘two wavy lines and thermometer’ warning light on dashboard
- It means your car is overheating and you may need to replace the antifreeze
Motorists often scratch their heads over the meaning of various warning lights on their car’s dashboard.
But drivers should learn the meaning of a red symbol that looks like two wavy lines with a thermometer sticking out.
Not knowing what this means could cost them dearly as they wouldn’t realize their car was overheating before it was too late, putting them at risk of being stranded and costing thousands in repairs.
Some cars have an illuminated dashboard symbol that warns the driver if the car is overheating – the engine cooling warning light.
The engine cooling warning light is the most unrecognized dashboard symbol among British motorists, according to a survey by ATS Euromaster.
Drivers are shocked by the meaning of the red warning light on the dashboard, which looks like two wavy lines with a thermometer sticking out – it means your car is overheating
While many think it’s obvious, others who’ve seen it light up aren’t sure what the symbol means.
“What does the symbol that looks like a thermometer/tree in the water mean in a car?” one user asked on Twitter.
And another user, who wasn’t bothered by their car’s warning, wrote, “I just keep ignoring the squiggly lines on my dash. I don’t need any more unexpected bills this month.’
But a concerned co-driver urged them to get it checked, replying, “Squiggly line under a thermometer symbol, you need to check your coolant ASAP.”
The warning light tells the driver that the engine is overheating, so if you see the light come on while driving, stop and turn the engine off as soon as possible.
You should then open the hood and leave your car turned off for at least half an hour to cool down, the RAC says.
Never remove the radiator cap or expansion tank cap from an overheated engine as it is under pressure and can cause severe steam burns.
If your engine gets too hot, it can cause expensive damage to your car. You can even irreparably damage the engine.
Experts at Halfords say that constant overheating, or the warning light flashing regularly, usually also indicates that the engine coolant level is running low, so topping up is probably the top priority. If this does not solve the problem, there may be another problem. and you need to contact a mechanic.
Engine coolant: Check and top up
Cars use engine coolant, also known as antifreeze because it does not freeze at low temperatures, to dissipate the heat generated by the engine.
Vehicles usually have a coolant reservoir with minimum and maximum fill level marks – when the engine is cold, the level should be between the two marks.
Once the engine has cooled down, check the coolant level. If it is too low, top it up with a mixture of antifreeze and water as indicated by the specific coolant being used (or a premixed antifreeze) by pouring it into the reservoir.
In an emergency you can use clean tap water, but never cold water if you don’t have antifreeze on hand – but this should be added as soon as possible.
Overfilling the antifreeze reservoir can damage the entire cooling system.

Many drivers wouldn’t know if their car was overheating before it was too late, risking them getting stranded somewhere in the middle of nowhere – and saving thousands on potential repairs (stock photo)
If topping off the coolant won’t get your car to work or if it’s full, you’ll need to call the tow truck to pick you and your car up, and the problem could be more serious.
Antifreeze’s effectiveness fades over time as it degrades, so your engine won’t be able to keep cool as efficiently. If it continues to do so, it can cause problems much more expensive than a bottle of coolant.
Antifreeze should be replaced every three to five years – depending on how often you use your car, its age and the temperature of where you drive.
If your car is constantly overheating despite a new change of antifreeze, it is possible that the cooling system in your car is leaking, so you should have this checked by a mechanic.
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