Engine Fire: What It Is, Warning Signs and What to Do

The Short Answer: What to Do If Your Engine Is on Fire

Signal, pull over as soon as it is safe and stop away from buildings, other vehicles, dry grass and fuel pumps. Turn off the ignition. This stops fuel delivery and shuts down many of the electrical systems that can feed the fire. Get every occupant out and leave belongings behind. Help children and anyone with limited mobility first. Move well away from the vehicle, upwind if you can, and keep other people back. Never go back for possessions. Call emergency services (911 in the US). Give your location, say it is a vehicle fire, and say whether the vehicle is electric, hybrid or carries fuel or cargo. Do not open the hood. Fresh air can make the fire flare suddenly, and the hood latch and panel may be very hot. Use a portable extinguisher only if the fire is small, you have a clear escape path, and you can aim through the grille or wheel well without opening the hood.

What Counts as an Engine Compartment Fire

A vehicle fire can start in several places, including the cabin, the cargo area, under the vehicle near the exhaust or in the wheels and brakes. An engine compartment fire is set apart by where it starts. It begins in the area where heat, fuel, oil and electrical power are packed most closely together. That is why it is one of the more common types of vehicle fire. It is also why it can spread quickly into the cabin through the firewall, the bulkhead between the engine bay and the passenger area.

Every fire needs three things: an ignition source, combustible material and oxygen. Under the hood, ignition sources include hot exhaust parts, electrical arcing and sparks. Combustible materials include gasoline, diesel, engine oil, transmission fluid, power steering fluid, coolant (which can burn under some conditions), plastics, rubber hoses, insulation and debris such as leaves or nesting material. Air reaches the engine bay through the grille and from below. The basic idea is to remove one of the three. Turning off the engine cuts fuel and power, and an extinguisher interrupts the chemical reaction or smothers the fuel.

Common Causes of an Engine Fire

Most engine fires trace back to one of a few failure patterns. Which ones apply depends on the vehicle, its age, how it has been maintained and its powertrain.

Cause | How it leads to fire | Typical contributing factors; Fuel system leaks | Gasoline or diesel drips or sprays onto hot surfaces or near sparks | Cracked fuel lines, failed injector seals, loose fittings, aging rubber components; Oil and fluid leaks | Oil or other fluids reach the exhaust manifold or turbocharger and ignite | Leaking valve cover gaskets, a missing oil filler cap, overfilling, recent sloppy servicing; Electrical faults | Short circuits or loose connections cause arcing and melt insulation | Damaged wiring, poorly installed aftermarket accessories, corroded battery terminals, rodent-chewed wires; Overheating | Extreme temperatures break down hoses and seals and can ignite nearby materials | Low coolant, a failed water pump or fan, sustained heavy loads; Exhaust and catalytic converter heat | Very hot exhaust parts ignite fluids, debris or materials underneath | Engine misfires sending unburned fuel to the converter, parking over dry vegetation; Debris and nests | Leaves, paper or rodent nests catch fire from engine heat | Vehicles parked outdoors or unused for long periods; Recall-related defects | A known design or manufacturing flaw creates a fire risk | Specific models and model years named in a recall notice

Warning Signs Before a Fire Starts

Many engine fires give some warning first. Treat any of these as a reason to stop and check, or to have the vehicle inspected soon:

Smoke coming from under the hood, the grille or the wheel wells; A smell of burning plastic, rubber, oil or fuel; A strong fuel smell while driving or after parking; Fluid puddles under the vehicle, especially fuel or oil; Fuses that keep blowing, flickering lights or other unexplained electrical faults; A temperature gauge rising quickly or a warning light for overheating; A flashing check engine light, which on many vehicles indicates a misfire that can overheat the catalytic converter; Rapid, unexplained changes in fuel level or oil level

Smoke is not always fire. Steam from a coolant leak is usually white and smells sweet. Oil burning on the exhaust tends to give blue-gray smoke with an acrid smell. Still, it is hard to tell these apart from the driver's seat. If you see smoke you cannot explain, follow the same steps as for a suspected fire: pull over, switch off and get out.

Safe Evacuation and Why Distance Matters

Safe evacuation is the most important part of responding to a vehicle fire. A fire can spread from the engine bay into the cabin, and burning plastics give off toxic smoke. Other parts can fail violently in the heat, including gas-filled struts, bumper absorbers, tires and sealed containers. Once everyone is out, stay well back and keep out of traffic lanes. Use the shoulder, a barrier or the far side of a guardrail where you can. Watch for smoke drifting toward you, and move again if the wind shifts.

If the vehicle is on a busy road, turn on hazard lights before leaving if it takes no extra time. Do not stay in the vehicle to set up warning triangles or gather items. When firefighters arrive, tell them what you saw, where the smoke or flames started, whether anyone is still unaccounted for and what type of powertrain the vehicle has.

Using a Fire Extinguisher: Ratings and Limits

A small, properly rated extinguisher can put out an early engine fire, but only when the risk is low. Fire extinguisher ratings in the US use letter classes for the types of fire an extinguisher is designed to fight. The numbers alongside the letters show its relative capacity.

Class | Fire type | Relevance to an engine fire; A | Ordinary combustibles such as paper, cloth and some plastics | Interior materials and debris; B | Flammable liquids such as gasoline, diesel and oil | The most common fuel in an engine compartment fire; C | Energized electrical equipment | Wiring, battery and electrical components that may still be live

For a conventional vehicle, a multipurpose dry chemical extinguisher rated for classes A, B and C is a common choice. A B:C rated unit also covers the main fuel and electrical risks. Store it secured, where you can reach it, because a loose extinguisher can become a projectile in a crash. Check its pressure gauge regularly and follow the maintenance or replacement guidance on the label.

If you decide to use one, keep your escape route behind you. Do not lift the hood. Aim the discharge through the gaps in the grille, under the vehicle or through the wheel well, at the base of the flames rather than at the smoke. Use a sweeping motion. If the fire does not shrink quickly, or if it reaches the cabin, the tires or the fuel tank area, stop and move away. A typical portable extinguisher empties in a short time, and an engine fire can reignite after it seems to be out.

Electrical Isolation: What Not to Attempt

Electrical isolation means cutting the power supply to stop electrical faults from feeding a fire. Turning off the ignition does part of this. Do not try to disconnect the 12-volt battery while the fire is active or the engine bay is smoking. Reaching under the hood exposes you to flames, hot surfaces and a sudden flare-up when the hood opens. Leave further isolation to firefighters. After the fire is out and the vehicle has cooled, a technician may disconnect the battery before inspection or towing.

Electric and Hybrid Vehicles: How They Differ

Electric vehicles (EVs) and hybrids still have a 12-volt system and some components under the front hood. Their main fire risk is often the high-voltage traction battery, usually mounted under the floor or rear seats. A damaged or faulty lithium-ion battery can go into thermal runaway. This is a self-sustaining chain reaction in which the cells heat up, release flammable gases and ignite one another. These fires can be hard to put out. They may give off large amounts of toxic smoke and can reignite hours or even days later.

For an EV or hybrid, do not try to fight a battery fire with a portable extinguisher. Get out, move well away and tell emergency services the vehicle is electric or hybrid so responders can plan their approach. Hissing, popping or venting smoke from beneath the vehicle can signal battery trouble even without visible flames. A plug-in hybrid also has a fuel system, so it carries both conventional and battery-related fire risks. Response and post-incident handling guidance varies by manufacturer and model.

After an Engine Fire

Do not try to start or drive the vehicle, even if the damage looks minor. Wiring, fuel lines and brake components may be compromised. Have the vehicle towed to a repair facility, or held where your insurer can inspect it. Photograph the damage once it is safe and keep any service records, especially for recent work under the hood. Contact your insurance company. Fire damage is typically handled under comprehensive coverage, but terms vary by policy. Check whether the vehicle has an open recall. You can search by vehicle identification number (VIN) through NHTSA's recall lookup or the manufacturer. If you believe a defect caused the fire, you can also file a vehicle safety complaint with NHTSA. For EVs, tell the tow operator and repair shop about the fire, because damaged battery packs may need special storage and handling.

Reducing the Risk of an Engine Fire

Prevention mostly comes down to keeping fuel and fluids contained, wiring intact and heat under control:

Follow the manufacturer's maintenance schedule and fix fluid leaks promptly. After oil changes or other service, make sure caps are fitted and no rags, tools or spilled fluid are left in the engine bay. Have a flashing check engine light, a burning smell or repeated blown fuses diagnosed rather than ignored. Use qualified installers for aftermarket electrical accessories, and avoid improvised wiring. Clear leaves and debris from the engine bay and cowl area, and check for signs of rodents in vehicles that sit for long periods. Avoid parking over tall, dry grass, since exhaust components can stay hot after the engine is switched off. Respond promptly to recall notices, particularly those involving fire risk. Keep a properly rated, secured extinguisher in the vehicle and know how it works.

Key Takeaways

An engine fire happens when an ignition source meets combustible material under the hood. Common causes are fuel or oil leaks, electrical faults, overheating and debris. Warning signs such as smoke, burning smells and electrical problems often come first. If the fire starts, your priorities are to stop, switch off, get everyone out, move away and call emergency services. Fight it only if it is small and you can do so without opening the hood or putting yourself at risk. Electric and hybrid vehicles add the risk of a battery fire, which should be left to professionals.