It’s a beautiful day outside. The sun is shining and the weather is perfect. You slide into your car, ready to start your busy day, when uh oh! your car won’t start.
There are many reasons why your car won’t start. Before calling for help, there are things you can check yourself. For starters, make sure the steering wheel isn’t locked.
An empty gas tank is another simple reason why your car won’t start. If you were low on fuel before (or your gauge is broken), it’s possible you’re just on “E.” Take a look at some common reasons why you’re stuck and what you can do to get back on the road.
Top reasons why cars won’t start
1. Dead Battery
A dead battery is the most common reason why your car won’t start. The battery is what the car uses to provide electrical power to the entire car and electrical components (e.g., lights, radio, etc.). While the vehicle is running, the alternator charges the battery. If the battery is not charged sufficiently, you will not be able to start the car or use any electrical components.
Your battery can die for a variety of reasons:
- Your headlights or dome light was left on overnight or for too long
- You have a loose wire
- The water inside the component evaporated, leading to poor conductivity
- The battery’s lifespan has expired
Some common symptoms include:
- None of the electrical components work (e.g. the lights, radio, etc.).
- The battery light is on.
One way you can test to see if the battery is the problem is by jump-starting your car. If the jump start works, you’re most likely dealing with a dying battery or an alternator that is just having trouble recharging the battery. Consider replacing the battery or alternator, cleaning the connections, or having a technician do the service for you.
2. The Battery Connection Is Bad.
This is less common, but still possible. If your car won’t start, the cable connections on the battery might be bad or loose. Try turning them. If they move, the terminals are loose and need to be tightened. If they show corrosion or are otherwise dirty, they should be cleaned or replaced before being reattached.
Since you’re likely going to be dealing with metal tools around a battery it pays to be very careful and know what you’re doing—or just have a professional do it.
3. Faulty starter
A broken starter is another common reason your car won’t start. A starter is an electrical motor that is connected to the battery. Its role is to set the engine (i.e., pistons, crankshaft, etc.) in motion when you turn the ignition switch on.
Once the engine starts and is in motion, the starter’s job is complete. If the starter goes bad, the engine will not crank properly or may not crank at all when you turn the ignition key on.
If you hear a clicking noise when you try to start your vehicle, a broken or weakened starter could be the reason why your car isn’t starting. This is very similar to the bad ignition switch example listed before.
Some common symptoms include:
- The car is not starting when turning the ignition key.
- Hear a loud clicking sound when turning the ignition key, but the engine does not start.
- Very noisy when trying to turn on your car.
4. The Alternator Is Bad.
If you can start the car but it stalls or you’re experiencing interior lights that start out bright and then dim, the alternator could be the culprit.
The battery symbol may also appear on the dashboard and you may even notice a burning smell since the alternator works with belts. There’s no quick fix, so you’ll want an expert to take a look. If it’s bad, it might have also damaged the battery.
5. Electrical or Wiring Problems
Nearly 5% of non-starting cars we attended had an electrical problem or an issue with the wiring. These included issues with the fuse box, with battery cables, or with the body control unit.
Remember that rodents can nest under the bonnet of your car and gnaw the wiring if it hasn’t been driven for a while.
6. Engine Problems
Problems with the mechanics of your car’s engine can stop the car from starting. The main culprits are usually the crankshaft or the timing belt and timing chain. Altogether, they make up over 3% of non-starting cars we see.
This could be the problem if the engine won’t turn over or starts and stalls.
7. Faulty Immobilizers
Sometimes, your car’s security system might actually stop you from starting the car if it doesn’t recognize your key. This might be because of the battery in your key fob’s low. Alarm and immobilizer issues make up nearly 3% of the breakdowns we see.
Try holding your fob right against the start button or try a spare key. If it’s still not working or you don’t have a spare, you might need to get a new key.
8. Defective ignition switch
If you know your battery is working properly, but your car doesn’t turn over on the first few tries, you might have a problem with the ignition switch. You can try to narrow down the cause of your issue by turning on your headlights.
This is because your car’s battery controls your headlights and dashboard, and if it’s the case that they turn on your engine isn’t able to start start, then a bad ignition switch is the likely culprit.
9. The Timing Belt Needs To Be Replaced.
The timing belt is a rubber strip that rotates the cam and crankshaft in the engine at the proper time. If it fails, the engine won’t run. You may hear a ticking sound coming from under the hood or hear the starter motor engage but not turn over.
This is less common than other possible issues, as timing belts typically break while the engine is running (which can be very bad) and some cars now come with chain belts that last longer than the rubber version. Either way, it will require a trip to the repair shop.
10. Clogged fuel filter
If your fuel filter is clogged, the gasoline won’t be able to reach the engine. This makes it difficult for your car to burn the fuel it needs to get going. Fuel filters should be changed every 15,000 to 20,000 kilometers, so consider swapping fuel filters next time you get your car serviced.
11. The Distributor Rotor and Cap Are Broken.
A distributor is responsible for directing electricity to spark plugs, which ignite the fuel. If the cap isn’t on tightly or the rotor isn’t functioning, the spark won’t travel. The good news? Most newer cars use individual coil packs that replace the distributor. In older cars, a bad cap may lead to noises like tapping or sputtering. Get a pro to replace it.
12. The Steering Wheel Is Locked.
If your car’s steering wheel gets stuck in a locked position, it may not allow the car to start. (You really, really want to be able to steer a car in motion.) Don’t yank too hard on the wheel. Instead, use a side-to-side motion with the key in, or use a duplicate key if you can. Your current one may be worn and unable to communicate with the lock tumblers.
13. Spark Plugs
Our mechanics see hundreds of cars every month that won’t start due to issues with the spark plugs.
A common issue is a flooded petrol engine. This happens when the engine’s switched off too soon after being started from cold. The unburned fuel which entered the engine remains there after you turn if off. That wets the spark plugs and makes it hard to restart the car.
It could be a flooded engine if you hear a very fast cranking sound when you turn the key (usually a ‘whirring’ sound). You might also notice a strong smell of petrol or the car may start briefly and cut out again.
14. Low AdBlue
If you’ve run out of AdBlue, you won’t be able to restart the engine. You may have to call out a mechanic as some car models need software to restart them.
It’s easy to avoid running out though – your car will show you a warning with a countdown on the dashboard to give you time to top up.
15. The Car Is Out of Gas.
Sometimes, the solution to a problem is simple. Don’t overlook the fact you might need to fill up your gas tank before hitting the road. And try not to let your tank run low too often. In cold weather, moisture from the air inside the tank can freeze, creating ice that can mean trouble for the engine.