Why Won’t My Car Start?

Reasons Why A Car Wont Start

The other day I was all ready to pick up my kids from soccer practice. I went out to my car, and it just wouldn’t start. I couldn’t believe it! I sat there, in the driver’s seat, thinking, “Why won’t my car start?” to myself.

I did an internet search to try to narrow down the reasons why won’t my car start. If I had to hazard a guess, I would say you did the same thing, which lead you to this article. Since you’re here, I’m going to share what I found out. Maybe it will help you too.

It’s hard to tell why your car won’t start without knowing about the condition of your vehicle before this particular incident. Do you change the fuel filters regularly? Did you forget to fill up the gas tank? Is the starter making a clicking noise? Don’t despair. There are a few common problems that you can eliminate before calling the mechanic.

The most widespread reasons that your vehicle won’t start are:

  • Dead battery
  • Bad alternator
  • Broken starter
  • Bad ignition switch
  • Empty gas tank
  • Clogged fuel filter or injector
  • Compromised security system
  • Worn out spark plugs

Dead Battery

A dead battery is by far the most common cause for a vehicle not starting. Even if your battery was fully charged when you turned off the car last night, something simple could have drained all its power in a matter of hours. Leaving your lights or your phone to charge while the engine is off on are prime examples of battery draining acts.

To determine if your battery is dead, try starting the car with jumper cables. If the vehicle starts with the jumper cables, then the issue is the battery. If it doesn’t, then there is another problem.

To jumpstart your car:

  1. Park your vehicle and a second vehicle that has a working battery with the hoods facing each other.
  2. Put both vehicles in Neutral or Park.
  3. Turn off the car with the good battery.
    Turn off and unplug anything that might be draining the other car’s battery (lights, radios, chargers).
  4. Open the hood of both vehicles.
  5. Connect either end of the positive red jumper cable to the (+) red post of the dead battery.
  6. Attach the opposite end of the positive red jumper cable to the (+) red post of the charged battery.
  7. Fasten one end of the negative black jumper cable to the (-) black post of the charged battery.
  8. Fix the other end of the negative black jumper cable to an unpainted metal part in the dead car to ground the circuit.
  9. Turn on the car with the good battery and let it idle for about ten minutes.
  10. Turn the engine off and remove the cables in the following order: (-) negative black grounded cable, (-) negative black cable attached to the charged battery, (+) positive red cable attached to the functioning battery, and finally (+) positive red cable connected to the dead battery.
  11. Do not let any clamps touch any metal surface which disconnecting.
  12. Start the car with the dead battery.
  13. Let it idle or go for a drive of at least 5-miles so the battery can recharge.

Another item that might cause battery failure is a loose cable. In this scenario, the battery still has a charge. However, it is unable to move the power to the starter because of the insecure or unattached cable. Take a minute to pop the hood open and check the wires. Make sure the wires in the cable aren’t corroded and are adequately insulated. If either of the cables is loose, use an open-ended wrench turning clockwise to tighten them.

If the cables are properly connected, the terminals on the battery or the clamps may be too dirty to complete the connection. Use a battery cleaner and a wire brush to clean the cable clamps and battery. Wipe them dry with a clean cloth before reconnecting.

Another cause might be the evaporation of water preventing the circuit in the battery. The fluid level in your car battery is critical. Some cells are maintenance-fee and will say so on the battery itself. Others need regular water top-ups for optimal power capacity.

Many conventional car batteries have a mixture of sulfuric acid and water. The plates in this type of cell should be continuously wet with this solution during charging when hydrogen and oxygen gas are released. Therefore, there should be just enough water in the wells to cover the exposed plates.

Water should only be added after charging. So if a dead battery is likely, charge it completely before filling the wells. The water level should only be about 3 / 4 full, so be careful not to overfill them. Never add sulfuric acid. If too much water is added, the solution will expand during battery use, overflowing, and potentially damaging the battery.

Too much water will also unbalance the sulphuric acid level and result in reduced performance. Don’t use regular tap water. Instead, use distilled, deionized, or demineralized water. Tap water often contains minerals and water softeners, which can damage the battery.

Bad Alternator

The alternator recharges your car battery after use. If the alternator fails to do that, the battery will die once all the stored power has been used. If the alternator is malfunctioning, usually the battery warning light will turn on.

While a jump start may get your car started briefly with a bad alternator, the car battery won’t charge, and your vehicle won’t run. To repair this problem, you’ll need to replace or repair the alternator.

Broken Starter

If the battery isn’t the issue and your car makes a clicking noise when you turn the key in the ignition, the problem might be a faulty starter.

If you know what piece to look for under the hood, you could try this trick. Tap the starter with a hammer gently. If the issue is a starter with a gear that is stuck, the tapping could loosen it enough for the starter to work correctly.

If you don’t know what the starter looks like, don’t randomly bop pieces with a hammer, hoping you’ll get the right one. You could damage your vehicle or injure yourself in the process. If you aren’t sure which part is the starter, you can try another method. Activate the handbrake level while the car is in the highest gear. The rocking that results may loosen a jammed starter gear.

However, the only sure-fire way to start your car when the starter is faulty is to replace it.

Bad Ignition Switch

The ignition switch sends power from the battery to the car’s electronics. There are four positions the ignition switch can be in. These are:

  • Lock/off
  • Accessory
  • Run
  • Start

When the ignition switch is in the off or lock position, all power to the circuits is cut — additionally, the steering wheel locks. If your vehicle has an automatic transmission, this is also locked. You can not remove or insert your key in this setting.

While the ignition is in the accessory position, battery power is sent to the car’s accessories but not the engine. So you can turn on the radio in this setting, but the car won’t start. In the run position, power is sent to the engine controls to prepare to start the motor. Only in the start position is enough power sent to ignite the motor and run all the accessories.

A bad ignition switch might be the culprit why won’t my car start if:

  • The engine stalls.
  • The car won’t start.
  • Accessories and dashboard lights flicker.
  • You can’t turn or remove the key.
  • The engine continues to run after you remove the key.

The ignition switch includes both the lock cylinder and switch. These parts can be replaced as a unit or separately. Ignition switches are often damaged by heavy keychains pulling down on the mechanism. If you have a lot of keys, consider putting the ignition key on a separate keychain.

If the reason why won’t my car start is the ignition switch, you should not waste any time in getting it replaced. Your vehicle could shut down as you are driving or leave you stranded along a dark and scary back road.

Unless you are experienced in replacing the part, let a mechanic do it. Because replacing the ignition switch includes disabling the steering column, if done incorrectly, the airbags might be activated, causing you injury.

Empty Gas Tank

Although you have a fuel gauge on your dashboard that should indicate how much gas is in your gas tank, it may not be working correctly. So to find out why won’t my car start, I can take a few minutes to check the gas level with a dipstick manually.

A dipstick is a measuring device that can measure inches of fuel or gallons of gas depending on if it is calibrated or not. A calibrated dipstick takes the guesswork out of determining how much gas is in the tank.

To calibrate a dipstick:

  • Begin with an empty gas tank.
  • Add one gallon of gas.
  • Insert the dipstick.
  • Remove the dipstick.
  • Mark the wet line on the stick.
  • Add additional gallons in increments.
  • Repeat dipping and marking procedures until the gas tank is full.

Clogged Fuel Filter or Injector

If there is plenty of gas in your gas tank, you may have a clogged fuel filter or injector. Fuel filters should be changed every 10,000 to 15,000 miles. If dirt or sediment builds up on the screen, then the gas can’t move freely, and your car won’t start. .

A clogged fuel filter is the likely cause of problems starting, vehicle hesitation, and poor gas mileage. If the fuel filter hasn’t been changed in some time, then change it. Some have a clear window that lets you see inside. If it looks gummed up, dirty or dark, change the filter.

A similar problem that may prevent your vehicle from starting is a clogged fuel injector. Fuel injectors send gas to the engine by spraying gas into the combustion chamber, which lets it mix with air before ignition. Over time, residue can clog the fuel injector nozzle. Schedule your vehicle for a fuel injection flush if you suspect a clog.

Compromised Security System

Many vehicles are designed to work with an immobilizer, which prevents them from starting with the wrong key. Your ignition key and car key both have a chip. That chip needs to match, or the car won’t start.

If you have inserted the wrong key by accident, your security system may consider itself compromised and shut down to prevent what it sees as a potential breach and attempted theft. To fix this issue, you’ll need to reprogram your car keys. Directions to do this can be found in the owner’s manual or online.

Worn Out Spark Plugs

The spark plugs receive an electrical signal from the ignition coil to create a spark in the fuel-air mixture that is inside the combustion chamber. Failing or bad spark plugs prevent this spark from happening, causing the engine not to start. Spark plugs should be replaced every 30,000 to 50,000 miles.

If worn-out spark plugs are the problem, your vehicle will:

  • Have difficulty accelerating.
  • Have poor gas mileage.
  • Have a misfiring engine.
  • Hesitate.
  • Not start.

If any of these have occurred, you may need to adjust or replace the spark plugs.


There are many reasons why won’t my car start. This article only mentions the most common cause of vehicle inoperability. These are:

  • Dead battery
  • Bad alternator
  • Broken starter
  • Bad ignition switch
  • Empty gas tank
  • Clogged fuel filter or injector
  • Compromised security system
  • Worn out spark plugs

Listening for clicks, looking at warning lights on the dashboard, and manually checking for clogs, disconnections, or empty cavities are simple ways you can diagnose possible problems with your vehicle.

Brett Gordon

The engine behind editing at DigMyRide and the brains behind its build. During the day, Brett is a thirty-something dude from SoCal climbing the corporate ladder, but by night, he spends his time contributing to the online world of automotive tech & trends.