Question: Yesterday, when I pulled into my driveway after work, my car completely shut off before I even put it in park. I’m so thankful it didn’t happen any sooner! What would cause my car to shut off while I’m driving?
Answer: I’m so glad you made it home before anything more serious happened! Cars shouldn’t shut off while driving, and when they do, you’ll typically need to visit a mechanic. Most of the issues that might cause a sudden shut-off require specialized tools to diagnose and repair by an expert. They include:
A malfunctioning crankshaft position sensor
The crankshaft translates movement in the engine to movement of the car’s wheels. A malfunctioning crankshaft position sensor prevents the engine control unit from sensing the correct position and speed of the crankshaft, which can lead to stalling.
A broken mass airflow sensor
The mass airflow sensor helps ensure the engine has the right mix of air and gas for combustion, but a broken sensor can disrupt the balance of air and fuel. That could lead your engine to run inefficiently or stall unexpectedly.
A faulty fuel pump
A faulty fuel pump won’t send enough fuel to the engine, which can cause it to sputter and shut off while driving.
A damaged electrical system
The electrical system—including the battery, the starter, and the alternator—is the backbone of the engine. It supplies power to the fuel pumps, spark plugs, sensors and other components required for the engine to operate.
If your alternator isn’t working, it can cause your car to shut off by failing to charge the battery properly. Without sufficient electrical power from the battery, critical systems may fail, leading to engine shutdown.
Likewise, if spark plugs don’t have enough power, they’ll fail to create the spark that causes combustion. And spark plugs themselves can break, which also creates problems.
There are many more components that can cause electrical issues: a blown fuse, a bad wire, or faulty connections, among others.
A defective ignition switch
Here’s how your ignition switch works: After you insert your key, you rotate the ignition until you go through all the stages. Each stage—OFF, ACC, ON, START—turns on an increasing number of components.
- ACC turns on accessories, such as the radio, which aren’t necessary for the engine to run.
- ON turns on fuel pumps and other components necessary for the engine to run.
- START turns on the engine. Once the engine is running, the switch springs back to ON.
A defective ignition switch can cause your car to shut off while driving by failing to maintain the electrical connection required to keep the engine running.
Empty fuel tank
An empty fuel tank is an obvious, yet sometimes overlooked, cause of a car shutting off while driving. Fuel is the engine’s power source, and losing fuel can cause the engine to stall or stop.
If you have an OBD-II scanner, you could diagnose the problem using the trouble codes it displays. It’s more difficult to get a good read if your car shuts off occasionally, though.
That’s why your best bet is to get a mechanic to take a look at your car. With a series of diagnostic tests, an experienced mechanic can identify where the problem originated and which parts need to be repaired or replaced to get it up and running.
Xuyun Zeng is a content strategist with a wide-ranging content background including tech, journalism, cars and health care. After graduating with highest honors in journalism, Xuyun led a newspaper to win eight awards, helped start an award-winning film industry podcast and has written over a hundred articles about cars repair, state laws and insurance. Prior to joining Jerry, Xuyun worked as a freelance SEO consultant with a mission to create the best content that will help readers and grow organic traffic.
Alice Holbrook is an editor with more than a decade of experience covering personal finance, including car insurance. She\’s passionate about creating easy-to-understand content that demystifies intimidating topics for readers. Previously, she worked for NerdWallet, and her work has been featured by Newsweek, The Washington Post and the Associated Press, among others.
