Car Won’t Start When Hot: Tips for Getting Back on the Move

Why won’t your car start when it’s hot? Let’s take a quick look at why, before discussing some ways you could fix the problem.

Why Do Cars Struggle in Hot Weather?

So it’s a hot day and your car won’t start. Why? It could be for any number of reasons.


It could be something to do with your fuel. If your engine gets too hot, certain vapours can cause obstructions, which can make it harder for fuel to circulate. This, of course, will make it more difficult for your car to start.

This isn’t really a problem with newer models, as most new cars are fitted with fuel injectors. Because fuel is kept in the injector at such a high pressure, you don’t really get the same issues with vapour, which means that your fuel will have no trouble circulating in hot weather.

So if you’re driving a newer car with a fuel injector and your car still won’t start in hot weather, you’ll have to look a little deeper to find the source of the issue.


It might be linked to your battery, as high temperatures can quickly drain your battery life. This is because batteries run on liquid, which can evaporate in the heat.


Or it might have something to do with your oil. Conventional motor oil can break down at high temperatures, which is why some drivers switch to thicker grades during the hot summer months.


Finally, if your car won’t start when it’s hot, it might be a sign that you’re running low on coolant. You can seriously damage your engine when it’s low on coolant. So get it topped up the moment you see that thermometer warning light on your dashboard!

Car Won’t Start When Hot – Tips for Getting Back on the Move

  • Check your coolant levels – If they’re too low, it’s time to top up your coolant. It’s best to do this when your engine’s cool, to avoid scalding yourself, and it’s vital that you don’t overfill your coolant levels. Follow the instructions on the container, as it may advise you to dilute the coolant before applying it. And don’t get any on you! It’s highly corrosive, which means you should also avoid splashing it on your car’s paintwork.
  • Change your oil – Consider switching to a thicker grade oil during the summer months. Talk to your mechanic if you’re not sure which is right for you.

If there’s nothing wrong with your coolant levels, your motor oil, or your battery, and your car still won’t start in hot weather, it could indicate a deeper issue with your engine. Your coolant temperature sensor might be broken, for instance, which means that the engine will “think” it’s hotter than it is. Or there could be an issue with one of the critical electronic components the engine uses to start.

In any case, it’s time to call a mechanic!

Make Sure Help is at Hand

If your car won’t start when you’re out and about, you could become stranded. Getting stranded when it’s particularly hot outside could soon get unpleasant, especially if you haven’t got much water to drink. That’s why it’s always a good idea to consider taking out breakdown cover when you buy insurance as a new driver.


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