What Should You Do If Your Car Breaks Down on a Highway?

A stalled engine, flat tire or sudden mechanical problem can leave a driver exposed to fast-moving traffic. Knowing where to stop and how to request help is more important than trying to diagnose the vehicle at the roadside.

Quick answer: If your car breaks down on a highway, stay calm, keep control, turn on your hazard lights and move to a safe exit or as far off the traveled roadway as you safely can. Request roadside assistance and tell the provider your exact location. If the vehicle is safely away from traffic, remaining inside with your seat belt on is often safest. If it is exposed to a collision risk or there is smoke, fire or another immediate danger, move to a safer protected location only when you can exit safely. Call 911 for an immediate emergency.

Why highway breakdowns require a different response

At highway speeds, drivers have less time to react to a disabled vehicle. A narrow shoulder, a curve, darkness or bad weather can increase the risk of a secondary collision. Avoid making a stressful situation worse by stopping abruptly in a travel lane, attempting a repair beside moving vehicles or standing directly in front of or behind your car.

  • If the vehicle still moves: Seek a nearby exit, parking area or wide shoulder without crossing traffic dangerously.
  • If you must use a shoulder: Stop as far from moving traffic as conditions safely allow.
  • Alert other drivers: Use your four-way hazard flashers.
  • Call for help: Share your direction of travel, exit or mile marker and vehicle description.
  • Choose the safest waiting place: Assess traffic exposure, weather and immediate hazards before deciding whether to stay inside.
  • Do not attempt risky roadside repairs: A high-speed shoulder is often a dangerous place to work on a tire or engine.

Six steps if your vehicle becomes disabled on a highway

  1. Keep the vehicle under control. Hold the steering wheel steadily, ease off the accelerator when appropriate and avoid abrupt braking or lane changes.
  2. Warn surrounding drivers. Turn on hazard lights promptly. Signal before moving to the roadside when needed and possible.
  3. Get out of active travel lanes if possible. Take an exit or reach a wide shoulder or other protected stopping place without forcing your way across traffic.
  4. Secure your stopped vehicle. Set the parking brake where appropriate, keep hazards operating and identify your location using a mile marker, exit number or navigation map.
  5. Evaluate immediate danger. If safely off the roadway, staying belted inside can reduce exposure to passing vehicles. If the car is at risk of being struck or smoke or fire is present, move to a protected location if there is a safe route.
  6. Request appropriate assistance. Call roadside service for a nonemergency breakdown; call 911 for a blocked travel lane, fire, injury or immediate danger.

Should you stay in your car or get out?

It depends on the location and hazards. When a vehicle is fully away from high-speed traffic, it may be safer to remain inside with your seat belt fastened while waiting for assistance. If the vehicle is stuck in or very close to moving lanes, or you believe it could be struck, safely reaching a guarded area beyond the shoulder may be preferable. Never open a door into traffic or attempt to cross high-speed lanes on foot. If the vehicle catches fire or fills with smoke, evacuate immediately by the safest available route and call emergency services.

What if your car stops in a travel lane?

Turn on hazard lights immediately and assess whether you can move to the shoulder without losing control. If the vehicle will not move, call 911 and report that the car is blocking an active lane. Do not try to push a disabled car through moving highway traffic. Whether occupants should remain inside or move to safety depends on the location, traffic, visibility and feasibility of a safe exit; follow any instructions from emergency responders.

Is it safe to change a flat tire on the shoulder?

Only if there is ample space and you can work without exposure to passing vehicles. On a narrow, busy or poorly visible shoulder, do not attempt a tire change. Arrange roadside assistance and tell the dispatcher about the traffic exposure. A rim or tire is replaceable; a roadside collision may be catastrophic.

How can you help others see a stopped vehicle?

Keep emergency flashers on and, if conditions allow, use reflective warning equipment. Never walk alongside moving traffic to place warning triangles when doing so creates a risk. Do not use road flares near leaking fuel or another fire hazard. At night or in bad weather, prioritize keeping occupants safe instead of stepping into traffic to make the car more visible.

What should you tell roadside assistance?

Give the highway number, direction of travel, the last exit or nearest mile marker, where the vehicle is positioned, and whether there are injuries or dangerous conditions. Describe the symptoms (flat tire, loss of engine power, smoke or overheating) without attempting a risky inspection. Provide your vehicle's color and model to make it easier to locate.

Can you prevent some highway breakdowns?

Before a longer drive, inspect tires and warning indicators, confirm there is enough fuel or charge for the route, and address known mechanical problems. Carry a charged phone and any emergency supplies appropriate for your location. Our tire inspection guide and pre-drive safety checklist cover basic preparation.

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Frequently asked questions about highway breakdowns

What should you do first if your car begins to lose power on the highway?

Keep control of the vehicle, turn on hazard lights, look for a safe exit or shoulder and move away from traffic if the vehicle can still be controlled safely. Do not make abrupt maneuvers.

Is it safer to stay in your car after a highway breakdown?

If you are safely off the roadway and there is no immediate danger, staying inside with your seat belt fastened is often safest. If your vehicle is exposed to traffic or there is smoke, fire or another immediate threat, safely evacuating to a protected area may be necessary.

When should you call 911 for a disabled vehicle?

Call 911 when a vehicle is blocking a high-speed lane, occupants face immediate danger, or there is a fire, injury or other emergency. For a breakdown in a safe location, contact roadside assistance or a tow provider.

Should you change a flat tire on a highway shoulder?

Avoid changing a tire when you would be close to moving traffic, especially on a narrow shoulder. Arrange professional roadside assistance from a safe location instead.

Should you use hazard lights if your vehicle stops on the freeway?

Yes. Activate emergency flashers to alert other drivers. If you have warning triangles, use them only when you can place them safely away from traffic; do not walk into a live lane.

What information should you give roadside assistance?

Provide the highway name and direction of travel, mile marker or nearest exit, your vehicle description, whether it is fully off the road, the nature of the problem and any immediate safety concern.

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Safety sources and further reading

Reviewed October 29, 2026. Choose the safest response for the actual traffic situation, and follow directions from emergency personnel.