Why Does My Car Stall While Driving?
There are many reasons why your car may stall while driving, which is why a mechanic is often necessary to diagnose the exact problem.
Written by Andrew Biro
Reviewed by Melanie Reiff
Table of Contents
- Why does my car stall while driving?
- What does it mean when a car stalls?
- Common reasons cars stall
- What to do if your car stalls while driving
- How to find cheap car insurance
- FAQ
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If your car stalls while driving, something has momentarily stopped the engine from functioning as it should, resulting in a loss of power. This is most often caused by issues with the fuel system, electrical system, airflow or vacuum leaks, manual transmission, or a faulty alternator.
Of course, trying to figure out exactly why your car is stalling is easier said than done, and typically requires a visit to the mechanic—fortunately, however,
licensed broker
and car insurance app Jerry
has assembled the following car repair
guide breaking down what stalling means, the possible causes for stalling, and what to do if your vehicle stalls while you’re driving.Why does my car stall while driving?
If your
car stalls while driving
, there are many reasons why that might be—the most common include issues with the fuel system (such as a clogged fuel filter), problems with the electrical system (such as a dying battery), airflow or vacuum leaks, transmission problems, or a faulty alternator.To know for sure why your car stalls while driving, you will need to take it to an auto repair shop to have the problem professionally diagnosed.
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What does it mean when a car stalls?
Generally speaking, “stalling” refers to the phenomena by which a car suddenly and momentarily loses power—for one reason or another—during which time the car engine will cease operation and stop turning, similar to what happens during an engine misfire.
If your engine stalls while you’re driving, you’ll likely experience the following:
- Loss of power
- A momentarily lapse in engine noise/engine may start to sputter
- Loss of power steering/steering may become difficult
- Loss of power braking/braking distance increases
MORE: Symptoms of a bad car starter
Common reasons cars stall
Unfortunately, many things can cause a vehicle to stall—we’ve included the most common causes below.
Problems with the fuel system
One reason your car may stall is due to issues with the fuel system—which includes the fuel tank, fuel filter, fuel pump, fuel injector, and so on—something that often includes a loss of fuel pressure.
Some of the more common problems associated with the fuel system are outlined below:
- Bad fuel pump: A bad fuel pump can result in a stalled-out car by depriving the engine of fuel, causing a low fuel pressure
- Fuel leak: If there is a leak in your fuel system, it can result in too-little fuel reaching the combustion chamber, throwing off the fuel-to-air ratio
- Clogged fuel filter: If your fuel filter has become oversaturated with contaminants, it can prevent enough fuel from reaching the engine, resulting in a loss of power when accelerating
Problems with the electrical system
Another reason your engine might stall is because of an issue with the electrical system, particularly the battery. If your battery is starting to die, it can cause your alternator to work overtime, resulting in a loss of power.
An altogether dead battery won’t cause stalling while driving, but it can cause stalling upon the first ignition. In this case, you won’t even be able to get your car out of the driveway or parking lot.
Problems with the spark plugs
In the same vein, bad spark plugs may be to blame if your car starts stalling, as they are in charge of delivering the spark that starts the engine’s combustion process. Should they fail—even temporarily—the operation of the engine will momentarily cease, resulting in a loss of accelerating power.
A faulty ignition coil—which serves to convert the low current from your car’s battery into a higher current—can produce similar symptoms and may cause the spark plugs to malfunction.
Vacuum leaks and obstructed airflow
Vacuum leaks are another possible cause for stalling, as they throw off the air-to-fuel mixture ratio in the combustion chamber by introducing unmetered air into the engine—should this happen, the fuel delivered to the chamber will not be enough to
Engine stalling can also be the result of improper airflow, most often caused by a blocked or clogged air filter—though a dirty mass airflow sensor is also a possibility.
Problems with the crankshaft and camshaft sensors
A stalled-out engine could also be the result of a faulty camshaft or crankshaft position sensor. This is the sensor that is in charge of determining which cylinder needs to fire to synchronize the fuel injector and coil firing sequence.
Alternator failure
Your alternator is responsible for charging your car’s battery. A faulty alternator will not deliver enough power to the battery, making it difficult for your car’s electronic components to run as they should.
Problems with the timing belt
Most internal combustion engines in cars today use a timing belt or timing chain to synchronize the timing between the top-end components of the engine and the crankshaft. If this belt were to slip, stretch, or snap altogether, the engine’s timing would be thrown off, resulting in a stall.
Problems with the transmission
Lastly, your car may stall out due to problems with the automatic transmission, especially if your particular transmission uses a converter clutch.
If your transmission is at fault, you’re likely dealing with a malfunctioning torque converter, contaminated or low transmission fluid, or a clogged transmission cooler system.
MORE: Can you jumpstart a car with a bad alternator?
What to do if your car stalls while driving
If your car stalls while you’re driving, the key thing to remember is to keep calm and not panic. Panicking will put you and other drivers at risk, which is why you should calmly turn on your hazard lights and navigate your vehicle to a safe place off to the side of the road.
Once you are safely out of oncoming traffic, switch your engine off and then try to restart the engine—this should fix the issue momentarily, at which point you can navigate your vehicle back onto the road and drive to your nearest automotive repair shop to have a mechanic diagnose the issue.
This will usually involve the use of an OBD-II scanner to scan your engine computer for error codes, as it removes much of the guesswork and makes troubleshooting easier.
Of course, if your vehicle won’t start again after you pull off to the side of the road, you will need to call roadside assistance or a tow truck to transport you to the nearest auto repair shop.
How to find cheap car insurance
Thankfully, finding cheap car insurance is a lot easier than dealing with a stalled-out engine—all you need is the licensed car insurance super app, Jerry.
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What are the symptoms of a car stalling?
Common symptoms of a car stalling include loss of power when trying to accelerate, a momentary lapse in engine noise, loss of power steering/sudden difficulty steering, and a loss of power braking/braking distance increases.
What causes intermittent stalling?
There are many reasons why your car may intermittently stall while in operation, but the most common include: a clogged fuel filter, not having enough fuel in the tank, a faulty alternator, a slipped or broken timing belt, bad spark plugs/ignition coil, a malfunctioning torque converter, or a damaged camshaft/crankshaft position sensor.
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