Car Shuts off While Driving

Car Shuts Off While Driving: Common Causes & Solutions

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If you’re a fan of Formula One racing sport, then I believe you’ve seen those super-fast cars lose power and suddenly stop in the middle of the racing circuit. What follows is a radio conversation between the disappointed driver and the team’s engineers saying, “I’ve lost power, I’ve lost power over”. Now, back to a real-life scenario, imagine you’re driving on a busy highway or you’re in the middle of traffic then suddenly, your car shuts off while driving?

Well, not only is it an annoying experience, but also a dangerous situation that can expose you to a serious risk of causing an accident, especially if there are speeding vehicles behind you. Now, let’s assume you safely manage to pull your car off the busy highway. One burning question you’ll ask yourself after this traumatic experience is why your car decided to give up altogether. In this short guide, we will try to shed some light by discussing eight reasons that might be the cause. Once we’re through, we’ll proceed to discuss five possible solutions that can help to troubleshoot this problem.


8 Reasons Make Car Shuts Off While Driving

1. Empty Fuel Tank

Now, one of the main reasons why 90% of the vehicles on our roads shut off unexpectedly is the lack of enough fuel. If you’ve been on the back of the wheels for quite a while, I believe you’ve had this experience at least once in your lifetime. Although some motorists underestimate the amount of fuel in their tanks and assume it’s enough, some are easily distracted by the day’s hassle and forget to check the dashboard to keep track of the amount of fuel they have.

Anyway, whether intentional or accidental, hiring a cab, or simply taking a walk to the gas station, not forgetting asking for a canister, is one of the most shameful situations you’re likely to face.

Now, apart from human error, another reason that can lead to an empty fuel tank is when your car has a faulty fuel gauge and you’re not aware. This means that you’re likely to get the wrong indication of the amount of fuel which can cause you to run out of gas unexpectedly.


2. Problem With the Alternator

Apart from hybrid vehicles, any other auto whether old or modern has an alternator. This part of the car is more like the car’s generator and is tasked with managing electrical issues within the car such as charging the car’s battery and powering your car’s electrical components. Now, just like any other mechanical component, alternators too can get faulty causing your car to suddenly shut off.

The alternator is usually bolted to the engine and is driven by a serpentine drive belt to generate power. Although it can last anywhere from 10 – 15 years without a replacement, it can suffer major issues over time such as worn-out contact rings, worn-out carbon brushes, and failed voltage regulators.

When this happens, you’ll receive alerts such as charging system warning light and dimming of the dash and headlights. Although your car will still shut off without warning, the good news is that alternators will never malfunction unexpectedly without giving you several alerts. In short, they wear off gradually.


3. Overheating Engine

Another reason that might cause your car to suddenly stop is engine overheating. As fuel burns in the combustion chamber, it creates heat that later becomes mechanical energy. With the help of the alternator, your engine then converts this energy into electrical energy to be used by your car’s electrical components.

Since the engine is the heart, it’s always susceptible to overheating. Therefore, to keep it within its normal operating range, a coolant is used to lower the temperature. In case there isn’t any coolant, then the pistons are likely to malfunction causing the engine to shut down unexpectedly.

Low engine oil, electrical issues, and bad catalytic converter are some of the other reasons that can cause your car’s engine to shut down. Since it’s at the heart of your car, your auto’s engine will need to be lubricated frequently to prevent friction. The battery should also be checked regularly to prevent electrical failure as this too can cause the engine to stop in case it detects low battery power.


4. Faulty Fuel Pump

For your engine to function properly, it requires a sufficient amount of fuel. Now, the fuel pump is the one responsible for supplying this steady flow of fuel to the engine through the intake runners. If the fuel pump has the slightest of problems, then it simply means that it won’t meet the high fuel demand the engine needs to run.

Once the pressure in the fuel rail drops due to lack of enough fuel speed, then it means that the engine is likely is suddenly shut off as it will generally run out of fuel. Sometimes, the fuel pump might not be the issue but rather the fuel filter itself. Remember, the fuel filter is assigned the duty of removing debris from the fuel before it’s pumped to the engine.

So, if the filter is already clogged, then it generally means there’s inefficient fuel being pumped to the engine which can cause the engine to shut off. Therefore, whether the problem is the pump or the filter, you need to have a mechanic check the car to diagnose the problem.


5. Issues With the Engine Control Unit (ECU)

If you’re driving a modern vehicle, then it probably has an engine control unit (ECU). An ECU is generally a small computer that’s connected to the engine to control every component associated with the engine to enhance its performance. It does that via special sensors connected to the engine to collect key on-road data such as the speed, air intake, fuel rail pressure, and crankshaft speed among others.

Since it’s a crucial component in your car’s engine, a small issue with the ECU can lead to a dreadful experience if you’re not careful. Thankfully, this component will alert you with a “Check Engine” light on your car’s dash meaning you have to rash your car to the nearest mechanic as soon as it’s humanly possible.

Some motorists might decide to ignore this alert which is not a good idea as it will cause the engine to suddenly shut off. For enthusiast DIYers, an erratic ECU can’t just be fixed easily. You will need to hire a professional mechanic to troubleshoot the issue and fix the problem.


6. Faulty Crankshaft Position Sensor

Now, if all the five reasons we’ve mentioned are not the cause of your car shutting off unexpectedly, then you might consider looking at our next reason. Speaking of sensors, the position sensor for the crankshaft is just another reason that can bring your car to a sudden standstill. Just like the ECU, the crankshaft position sensor is a component fitted in most modern cars. Its main purpose is to analyze the precise position of the crankshaft alongside its rotational speed.

This data is then transmitted to the ECU to make the necessary adjustments such as improving fuel ejection timing alongside other operating parameters. Since the crankshaft sensor is located on the engine’s block just above the starter, failure to operate properly means a disaster to the engine. The engine is likely to stall, vibrate, misfire, loose of acceleration and finally, shut off unexpectedly.

Just like some of the other problems we’ve mentioned, a faulty crankshaft position sensor can be fixed by replacing it with a new one.


7. Ignition System Dilemma

An erratic ignition system is another reason that can bring your car to an abrupt halt. In most cases, your car will suddenly lose power and shut off all the electrical components including the dash and the headlights. Now, how do you determine the problem is caused by the ignition system? Well, it’s pretty simple. You only need to turn the keys to ignite the car to see whether it starts.

The ignition system is complex and at the same time, a crucial component in your car’s drivability. Inside the ignition system, there’s an ignition relay (switch). When you start the car, the ignition relay will draw power from the battery and supply it to the car’s electrical components among them being the fuel pump and the ignition coil.

From the ignition coil, the power is transferred to the spark plugs which ignite the air-fuel mixture in the combustion chamber to start the engine. With such a massive task, the ignition relay can sometimes (though rare) be susceptible to damage caused by wear, damage caused by an accident or exposure to water. Once it’s faulty, there will be an insufficient flow of power to the combustion chamber which means less fuel will be burned to keep the engine working. This will hence cause the engine to stall, vibrate then shut down.


8. Faulty Electrical Cables

If the spark plugs, the ignition switch, the relay, and the alternator are all working properly, then the next possible explanation for your car’s abrupt stop is faulty electrical cables. But, before you can seal your car’s fate, you need to examine the battery first to ensure that you’re not dealing with an already dead battery. However, to rule out the battery issue, it’s quite uncommon for the battery to suddenly die when the car is already running.

So, the electrical cable failure is an explanation that will definitely stand on. When you start the car, the electrical cables are responsible for transferring electrical power to all electrical components in the car. If these cables are loose or faulty by any means, then it certainly means that insufficient or total loss of power will be transferred. This can make the engine stall then shut off without a warning.


5 Possible Solutions

As you can probably see, the reasons that cause your beloved car to shut off abruptly are way more than the possible solutions. Since we can’t discuss everything, we will hit the ones that are most important and common among most motorists.


1. Refuel the Car and Fix the Faulty Fuel Gauge and Pump

In most cases, refueling your car is all that’s needed to give it a fresh start. As soon as you’ve done that, the next step is to examine the fuel gauge to see whether it was responsible for the shameful mess. Is it showing empty even after refueling, showing full when the gas tank is empty or is it fluctuating between empty and full? These are just some of the signs you’ll see with a faulty fuel gauge which means you need to replace it.

If the problem is due to a faulty fuel pump, then you have to start by inspecting the screen filter for any dust and debris buildup to determine whether it should be replaced or not. Since the fuel pump is among the components that require electrical power to work, you need to inspect the wiring from the pump to the battery to ensure that it supplies sufficient voltage to power the fuel pump.

You should also consider checking the fuel filter for any exposure to harmful sediments and the fuel pressure regulator as it’s the one responsible for regulating fuel delivery.


2. Repair or Replace the Alternator

Your car’s alternator is a critical component that needs to be cleaned and thoroughly maintained regularly. Unlike some of the complex components in your car, a faulty alternator is pretty easy to identify from symptoms such as unexpected battery warning light, ignition problems, noise, and rapid battery drain.

Now, if you detect any of the aforementioned signs, then it’s likely that your car’s alternator is in a really bad condition. However, to rule out other possibilities, you’ll first need to perform some tests. The first test is to check the battery’s voltage using a multimeter. When the engine is on, the reading should be 14 and when it’s off, the reading should be around 12.

Another test is to switch the headlights on then ask a friend to check the intensity of the lights (any dimming issues) when you press the throttle. Finally, though dangerous, remove the negative terminal of your car’s battery and see whether the engine still runs without any interruptions. In case it stalls, then it means the alternator is not generating enough power to feed the engine. From these tests, your mechanic will be able to judge the intensity of the damage then determine whether to replace the alternator or not.


3. Tighten the Electrical Cables

As one of the major causes of your car’s abrupt shut off, electrical cables are some of the easiest to fix even by an armature motorist. Here, you only need to inspect the cables for any signs of wear then proceed to tighten them.

Start with the most obvious ones especially those that come from the battery and the fuse box. Locate them carefully and tighten them patiently to avoid damaging other components. In case the problem persists, then you can diagnose the battery or simply hire a professional mechanic to accomplish the task for you.


4. Take Your Car For Comprehensive ECU Inspection

If your car’s check engine light keeps flashing, then it definitely means there’s a huge problem with the ECU. Again, enthusiast DIYers will definitely not manage to troubleshoot let alone fixing this problem. You have to take your car to a professional car repair center for it to be diagnosed. In most cases, the “Check Engine” light on the dash is a trouble code initiated by the ECU. So, to read these trouble codes, you have to use an OBD2 scanner to read these codes from the ECU.

Once the trouble codes are read, your mechanic will know the root source of the problem and will hence proceed to troubleshoot the specific issue. Sometimes, your mechanic (with your permission) can opt to use a car ECU programmer to edit, tune, adjust or reprogram your car’s ECU chip data to change the performance of the engine, the brakes, the transmission and the airbags among other components.


5. Clean or Replace Components in the Ignition System

Now, how do you detect that your car’s sudden shut off was caused by an irresponsive ignition system? First, if the ignition relay fails, it will force the ignition system to continue drawing power even when the car is off thus draining battery power. Other signs are ignition unresponsiveness, a fried relay, and an engine stall.

To fix this problem, you need to locate the ignition relay from the fuse box (in the engine bay) then clean it thoroughly to remove any debris. You can use a certified cleaner such as ethanol and a piece of cloth to clean the relay. You also need to inspect the ignition coil to see whether it has any issues as it’s the one responsible for transferring power to the spark plugs.



The good news about most of these issues we’ve mentioned is that they don’t suddenly shut off your car without alerting you. These alerts can be in the form of signals on the dashboard or symptoms in the form of unfamiliar vehicle behavior such as vibrations, noises, and engine stalling. Now, if you’re the type of driver that constantly ignores some of these alerts, then there’s a higher chance that you’ll be busted.

So, to prevent your car from shutting off unexpectedly, it’s wise that you become more proactive with your beloved car and cultivate the habit of having your mechanic check the various components regularly to prevent surprises.

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