Top 10 Causes of a Car Fire

A design flaw in a vehicle usually isn't going to cause a car fire on its own, because there's no on/off switch for lighting a vehicle ablaze. The U.S. Fire Administration estimates that fewer than 1 percent of car fires are due to design flaws. Usually, the manufacturers catch these before incidents become widespread. They issue recalls to get the dangerous cars off the street and fix the problems.

Not all design flaws result in car fires, but any number of problems can make fires a lot more likely. Though some recent incidents will be used as specific examples on the following pages, it's worth noting that since 2012, most major car companies have recalled a total of almost 10 million vehicles — both gasoline- and electric-powered, due to a fire hazard.

Human error probably isn't going to be the direct cause of a fire in your vehicle — after all, being lazy isn't quite the same as striking a match and tossing it into the gas tank. But if you're sloppy about maintenance, your car may be more dangerous in general, and the increased likelihood of a car fire is just part of the greater risks you're taking. The U.S. Fire Administration found that mechanical failure was the leading cause of car fires.

Forgetting or neglecting to properly take care of your car can indirectly lead to a fire. That's because if you let broken parts, leaky seals or faulty wiring go without repairs, they can make your car a lot more hospitable to the conditions that cause fires. This is especially true for older and vintage cars.

An engine with a bad gasket is more likely to drip hazardous — and flammable — fluids. Just over 20 percent of car fires can be traced to electrical failure or malfunction. So just pop the hood every now and then and take a cursory look around for leaks and frayed wires.

Depending on the impact site, a car crash can spark a car fire. Most vehicles' crumple zones are designed pretty well, so the body and frame absorb the force of a blow and protect internal, dangerous spots like the engine, the battery and even the gas tank. But a hard enough hit is likely to cause fluid leaks and spillage, as well as heat and smoke. As we know, high heat and spilled fluids create perfect conditions for a fire.

Since it's hard for occupants of a crashed vehicle to see the extent of the damage while they're still inside, the threat of a fire might not be immediately apparent. That's why it's always best to get away from a damaged car as soon as possible. Consider yourself lucky if you're not trapped inside a crashed vehicle — even if it does go up in flames, at least you're a safe distance away.

Arson is the criminal act of setting a fire. Now, why would anyone deliberately set a car on fire? Most often, it's revenge. But it could also be to cover up evidence of another crime. Sometimes it's curiosity or old-fashioned vandalism, or it could be insurance fraud. And there are probably several more reasons, but that's best left to the investigators.

It's pretty easy to set a car on fire. Arson investigators often look for tampering with the fuel system or an electrical short. We aren't advocating this by any means, but we are saying that an arsonist is yet another reason your car might be ablaze.

Not long after the Tesla Model S was awarded the unofficial title of "the safest car ever" by the media (and by Tesla Motors), a Tesla Model S caught fire in the fall of 2013. That's never good, of course, but for Tesla, it was especially bad. The company had implied numerous times that its fully electric Model S was all but immune to the battery-related problems that have plagued hybrid cars and EVs of the past. Alas, a Model S traveling at high speeds hit a piece of debris that punctured the car's battery, and the battery behaved like any other battery would: it ignited. Several other Teslas have caught fire since the first one in 2013, though these types of fires are rare.

Chevrolet recalled about 110,000 of its Volt EV model years 2017 to 2022 for potential battery fire issues. The problem was traced to a hardware and software issue in the batteries. It's estimated that about one-third of fires in electric vehicles occur while the car is parked and unplugged.

But hybrid cars seem to be the most likely to catch fire, with gasoline vehicles coming in second. Cars that run only on electricity are a distant third. Of course, because there are more gasoline-powered cars on the road, they also account for the vast majority of total fires.

Overheating catalytic converters are a fire risk that's often overlooked, but it shouldn't be. Here's why: It's one of the hottest parts of your car and it runs the entire length of the vehicle. We mean the exhaust system.

Catalytic converters usually overheat because they are working too hard to burn off more exhaust pollutants than they're designed to process. In other words, if the car's engine isn't operating efficiently (due to worn spark plugs or any number of other adverse conditions), it doesn't burn the fuel properly, and a lot of extra stuff ends up in the exhaust system. The cat then must work extra hard to do its job, which makes it even hotter than usual.

An overworked (or clogged) catalytic converter can easily go from its normal operating temperature range of about 800 to 1,000 degrees Fahrenheit (648.9 to 871.1 degrees Celsius) to 1,400 degrees Fahrenheit (1,093.3 degrees Celsius). This causes long-term damage not only to the cat itself, but also to the car's surrounding parts and the environment, such as tall grasses. The car's designed to withstand the cat's normal temps, but it can't consistently cope with temperatures several hundred degrees higher. The catalytic converter itself won't catch fire, but it could in theory ignite anything nearby at such high temperatures, including other parts of the car.

An engine that overheats and causes a car to catch on fire is an especially good example of how one problem can lead to another. A car's engine probably won't overheat enough to simply burst into flames all on its own. But an engine can overheat and make its fluids, like oil and coolant, rise to high temperatures and begin to spill out of their designated areas of circulation. They drip, drizzle and spurt throughout the engine bay and onto the exhaust system, landing on other hot parts, where they can ignite and spread. Most often, drivers pull over before things get that bad.

In rare cases, like the late- 2012 recall of about 90,000 Ford cars equipped with a specific EcoBoost powertrain, an engine that overheats is sometimes a design flaw that's fixable with a software update — modifying the car's computer to help keep engine temperatures at a safer (lower temperature) threshold. Generally, though, an overheating engine requires mechanical attention.

The average car or truck has several flammable and highly dangerous fluids under the hood: gasoline or diesel fuel, engine oil, transmission fluid, power steering fluid, brake fluid and even engine coolant. All those fluids are circulating when the car is on, and all of them can catch fire if their lines, hoses or reservoirs take a hit. So even though one of the car's vital liquids is unlikely to start dripping with no warning — generally, something else has to go wrong first — the fact is that all of these fluids are flammable.

Combined with another aggravating factor, like a car crash or a failed part, the result could be a fire. Though such a blaze is most likely to start in the engine bay, where all of these dangerous liquids are concentrated, keep in mind that some of them, like fuel and brake fluid, do move along the entire length of the car.

Electrical issues take the second spot on the list because they're the second-most common cause of car fires. Car batteries are problematic, and not just the hybrid and all-electric vehicle battery pack types we've already discussed. A typical car's standard lead-acid battery charging cycles can cause explosive hydrogen gas to build up in the engine bay, and the electrical current the battery provides (along with faulty or loose wiring) can produce sparks that can quickly ignite a fluid drip or leaked vapors.

The electrical system's hazards aren't confined to the area under the hood, either. Electrical wiring runs throughout the entire car: through channels, into doors, under the carpet, and through powered and heated seats, just to name a few places where an unnoticed frayed wire could cause havoc.

Leaks in the fuel system are the most common cause of vehicle fires, so that's why they take the top spot on our list. A fuel system leak is really dangerous. We've already discussed that a lot of a car's fluids have corrosive, poisonous and flammable properties, but gasoline is among the most flammable.

Gasoline at a temperature of just minus 45 degrees Fahrenheit (minus 42.8 degrees Celsius) or above can quickly catch fire from a simple spark. It happens all the time and on purpose in a running car, after all, but it's contained by the engine. And gasoline that reaches 495 degrees Fahrenheit (257.2 degrees Celsius) will ignite by itself.

It's easy to see how fuel dripping onto hot metal and plastic parts can cause a fast-spreading fire, not to mention the spark from a tossed cigarette butt or other source.

The best way to reduce chances of a fuel system fire is to make sure the car is properly maintained and to keep it out of the situations we've already described. And if you ever smell gas in or around your car, find and fix the leak immediately.