Diagnosing A Car That Dies While Driving

7 Ways To Diagnose A Car That Dies While Driving, What It Means And What To Do

Updated: January 30, 2022

car won't start

It never fails. You’re driving along and without any warning, your car dies. My car did this, and at the worst time – driving on the freeway. Talking about scary. It turned out to be an irreparable electrical problem but there are many, less troublesome reasons that your car could be stalling.

Here’s how to diagnose the problem causing your car to die.

1.Warning light appears on the dashboard

car won't start and check engine light is on

What It Means: If you warning light appears on the dashboard, it means that most likely your car is experiencing a charging system fault. The warning light could be a battery light, voltmeter, charging system warning, “Service Charging System” or something similar. Ultimately it means there’s not enough current for the battery and other electrical systems.

What To Do: If your warning light is “Check Engine,” then you’ll need to use an OBD-II scanner to get the trouble code and see what’s wrong. Alternatively, you’ll need to check the battery casing, terminals and cables for signs of damage. You’ll also need to take a look at the charging system circuit and its wires, fuses and connectors. Finally, it’s worth checking the voltage regulator and alternator.

2.Engine stops and lights turn off


What It Means: This issue is most likely caused by damaged wiring connected to the battery. You can test for this easily (see below). Additional problems could faulty ignition switch, a blown fuse or a broken fusible link. If your headlights are still working, then it could be the former, but if both lights and other accessories are not working, then it’s more likely the latter two.

What To Do: With your car in park (and parking brake engaged), you need to start the engine and idle with the lights on. Open the hood and take a look at what’s going on underneath. Jiggle the battery cables and see what happens. If the engine and lights shut off then the problem is the wiring. If they stay on, then investigate the ignition switch and fuses.

3.Engine dies after running briefly

engine dies after running briefly

What It Means: What’s likely happening here is your car’s ignition coils are suffering from what is known as electrical “opens.” These don’t impact your engine when you start from cold because they need to heat up before any fault will occur. The fault usually lies within your ignition coil, ignition module, crankshaft position sensors and fuel pump motors.

What To Do: You’ll need to test for opens on the crankshaft position sensors and ignition coils. Using an ohmmeter, you can test the crankshaft sensor resistance and compare it to the recommended levels as indicated in your owner’s manual. For the ignition coil, use a hairdryer or hot air gun to apply heat and then repeat the ohmmeter check. 

4.Engine shuts off at stoplights

What It Means: This usually points to a problem in your car’s idle air control (IAC) solenoid. The onboard computer uses this solenoid to inject more air, bypassing the throttle valve. If the valve gets a carbon or other contaminant buildup on it, then air can’t get through the ports when needed and a stall becomes inevitable.

What To Do: Take a look around the throttle body and you should find the IAC solenoid and its electrical connector. Unplug it and remove it entirely from the throttle body. You’ll then be able to check the passages for carbon or other contaminant buildups.

5.Engine shuts off while idling

What It Means: This is likely a similar situation to when the engine shuts off at stoplights but is likely more serious. It’s most probably caused by a vacuum leak. This is especially likely if your car has a mass airflow sensor. An alternative explanation could be a loose wire or bad engine speed sensor, which could be accompanied by a “Check Engine” light.

What To Do: For the vacuum leak problem, you need to check the brake booster, EGR valve, PCV valve and throttle gasket. What you’re looking for is signs of valves being stuck, carbon or other contaminant buildup hindering movement, and any other signs of damage. For the sensor issue, you’ll have to go through the fuel pressure regulator, MAF sensor, MAP sensor, ECT sensor and throttle position sensor to check for problems.

6.Engine shuts off while driving, but I can start it again

What It Means: This is probably a fault caused by something wrong in the car’s fuel system. It will mean that you stall possible while still moving slowly, or sometimes when you start to idle. The car dying is usually not so sudden, but rather you get a sense or warning signs that it’s coming, like the car jerking or sputtering. It will remind you of running out of gas.

What To Do: Three areas need checking to solve this problem. First is the fuel pressure regulator. Low fuel pressure might be causing the car to die in this way. Test it yourself using a fuel pressure gauge, or ask a mechanic to do it. Next is the fuel filter, which you’ll need to check for clogs. Clogged fuel filters also cause lowered fuel pressure. Finally, the fuel pump might be in need of replacement, especially if you haven’t changed it for a long time. The pump might not be delivering all the fuel that the car needs to keep idling.

7.Car suddenly dies

What It Means: This one often seems as though some ghost has come and turned off your ignition without you noticing. It doesn’t feel like a fault at first because usually other electrics are still working fine. The fault is most likely within your ignition system, or for newer cars it could be a malfunctioning sensor detected by the computer. It could be a bad contact in the ignition switch, or a sensor covered in debris buildup, or electrical wiring problems causing false readings in the sensors, among other things.

What To Do: There’s a laundry list of components to check, but they are all worth checking because all of them can contribute to this problem occurring in the first place. Start with the crankshaft position sensors and circuits, then the ignition switch and primary ignition system. Within the primary system, the fault might be traced to the battery, ballast resistor, ignition coil or ignition control module, or any combination of these components.

5 Common Causes Of Why A Car Dies While Driving

None of us want to experience the frightening feeling that our mechanical steed is dying beneath our feet. It’s a tremendously powerless sensation for the driver and can leave them feeling hopeless. Part of getting through these difficulties is understanding how the problems occur. Here are the 5 most common causes of why your car might die while driving:

1. Running out of gas

This could happen simply because you meant to get more gas but forgot and then didn’t have enough to make it to a gas station. It’s also more likely to occur if you have a faulty fuel gauge. Many drivers are caught unawares thinking they have a quarter of a tank or more but then suddenly sputtering to a halt. If you are lacking gas-filling organization, then you can quickly fix that with better habits, but if it’s a fuel gauge problem, then you should have a mechanic take a look at why it’s happening.

2. Faulty Ignition Switch

The repetitive process of starting, stopping, and starting the car over and over can cause wear and tear on the car’s ignition switch. When this happens, the engine will only be kept running when things are smooth and there is no disruption. It’s like knocking over a house of cards. If the switch is worn, and you run into some uneven road surface, a pothole or other obstacle, then the disruption to the delicate balance causes the car to die.

3. Alternator Problem

Your car’s alternator is what actually provides most of the electricity that it needs to operate. It also recharges the 12-volt battery by converting the engine’s mechanical energy into electrical energy. Therefore, if the alternator is experiencing problems and isn’t working properly, the car will be relying exclusively on the 12-volt battery to power the vehicle. This will work for a time, but with no new charge being delivered by the alternator, it will eventually run out of juice and the engine will die.

4. Malfunctioning Sensors

While newer cars still rely to some extent on old-fashioned mechanics, they increasingly rely on the correct functioning of an intricate and computerized network of sensors and digitalized controls. Sometimes, these sensors can send the wrong information to the Engine Control Unit (ECU), which results in erroneous warnings and misplaced fail-safes kicking into action.

5. Fuel Pump Fault

The fuel pump has the job of ensuring that the engine constantly has enough fuel to keep running smoothly. If the fuel pump becomes clogged, corroded, worn or its filters reach capacity, then less and less fuel will reach the engine, causing it to stall out. It’s not dissimilar to the way that a flagging battery can’t get enough power to its constituent components.

4 Things You Can Do If Your Car Dies While Driving

Before we get to the practical action steps you should take when your car dies on the road, the first thing we should remind all drivers is not to panic. Your car dying while driving is undoubtedly a tough experience, but it’s most likely a minor and easily solvable issue. Here is our advice:

1. Pull the Car Over Safely

Safety must come first and that means getting the car safely off the road and into a safe place. As soon as you detect any sign of trouble, start looking for a place to pull over. Keep your eyes fixed on the road and not on any warning lights or other dashboard indicators. You can check those when you’ve stopped.

If the engine actually dies while you’re still on the road, you should still have enough momentum and control to pull the car up carefully, steer into a space and brake to a complete stop.

2. Try a Restart

Consumer Reports reminds us that before anything else, you should attempt a restart. The first restart you can attempt is actually while you are still on the road. If you notice that your key has shifted to “accessory,” then you might be able to slip the car into neutral, restart the engine and continue.

If this is not possible however, you can first pull over, allow the car to come to a complete stop and then attempt a restart from there. Wait at least a few seconds before making the attempt. If your restart fails, then it’s time to move on to the next steps.

3. Activate Emergency Flashers

For safety reasons, regardless of whether it’s day or night, you should activate your car’s emergency flashers (hazard lights). They are usually activated by a prominently placed button on the center stack. It’s usually a red button with two white triangles or another color with two red triangles in it.

4. Call for Assistance 

With your emergency flashers active, you can now summon roadside assistance. If your usual mechanic is in range, stick with them to avoid any risk of unfair pricing. If you have roadside assistance as part of your ownership package, then contact the brand’s official assistance line for help. Not doing so might void the warranty or even the insurance.

5 Things To Do That Can Help Prevent Your Car From Dying While Driving

As with all things automotive, the best way to solve problems is to prevent them from happening in the first place. Below you’ll find our advice on steps you can take to stop your car from dying on the road.

1. Keep the Gas Tank Topped Up

As we mentioned above, the car dying can be caused by simply running out of fuel. If you maintain a good habit of keeping the tank topped off then you should be able to avoid this problem. If the problem is your fuel gauge, then you’ll need a mechanic to see to that, too. A false reading on the fuel gauge is at best problematic and at worst dangerous.

2. Don’t Use Heavy Key Rings

Heavy key rings weigh down on your car keys when they’re in the ignition slot. The result is that it’s easier for some to slip into the “accessory” (acc) position. As we described above, this can cause the engine to die and you may have to attempt a risky restart while you’re still moving on the road.

3. Keep Up with Maintenance

Your car’s engine is a finely tuned machine and needs to be well looked after. Besides the fuel and ignition systems (see below), you should always stay on top of your car’s regular required maintenance as a matter of course. Failing to do so will result in small problems turning into big ones, like your engine, potentially dying on the road.

4. Maintain the Fuel System

The various parts of the fuel system that were mentioned above such as the fuel pump, fuel filters, the EGR valve and other components all need to be in proper working order. These parts easily are subject to carbon and other buildups that block their functionality over time. Regular cleaning, changing and repairs are needed to keep all channels running smoothly.

5. Maintain the Ignition System

Similarly, the ignition system with its switches, alternator, ignition coils and other parts all need to be in proper working order. The natural operation of the engine causes these parts to wear and break down. Keep them maintained and you won’t experience difficulties.