Ask Car Mechanic

Ask Car Mechanic

How To Fix It

Car Won’t Start but Lights and Radio Work


Car Won’t Start but Lights and Radio Work

Car troubles can be very daunting when you don’t know where to start. If your car won’t start but the lights and radio work, you might be wondering what’s wrong– and how to fix this issue.

If your car won’t start but the lights and radio work, there are X things that can be causing this:

  1. Dying or leaking battery
  2. A faulty starter
  3. Corroded battery terminals
  4. A faulty ignition switch
  5. Problematic fuel pump
  6. Empty gas tank
  7. Blown fuses
  8. Faulty spark plug

If you are lucky, you may be dealing with one problem. However, there may be multiple issues responsible for your car failing to start, despite the lights and radio working. In this article, I’ll discuss the causes in detail, the signs, and how to fix the issues. Read on for more information.

1. A Bad Battery

Your car battery may be faulty even though the lights and radio work. It probably doesn’t have enough charge to power the engine. The radio and lights only need about 20 – 30 amps to work, while the engine needs at least 300 amps. A battery with a low charge can light the car’s accessories, but it doesn’t have enough power for the engine.

How To Fix It?

To confirm or rule out a bad battery as the cause of the problem, use a hydrometer to test the charge in your battery. If the battery has at least 12.5 to 12.6 volts, it is in great shape, so you need to look at other possible reasons your car won’t start. 

If the reading is 12.3V, the battery is running low and must be charged. Anything lower than 12.3V is a sign you need to replace the battery. 

Alternatively, you can use another car to jump your battery. If the battery accepts the charge and the car starts, then the problem is a low charge. If the battery charges but fails to start, you need to consider other potential causes.

I recommend using a product like this KONNWEI 12V Car Battery Tester (available on to analyze your battery’s health. I love this particular tester because it includes the voltage, charge status, AH capacity, and internal resistance. It also tests the starter’s condition. It is easy to use, 99.5% accurate, and reports in milliseconds.

Read: Why Car Speedometer Not Working?

2. Bad Ignition Switch

These are signs that you have a bad ignition switch.

  • The lights on the dashboard do not come on when you start the car. Sometimes the lights come on briefly before going off. 
  • The car stalls immediately when you start the car.
  • The key appears stuck, and turning the key is difficult. 
  • If you hear a clicking sound when starting the car, then the ignition switch is spoiled. You may also hear the clicking sound, but the engine does not come on. 
  • If you check the starter under the hood and find it is covered by oil, it is probably faulty. 

How To Fix It?

If the ignition switch is faulty, you need to replace it. If you are not comfortable removing parts from the hood, it is best to have your mechanic look at the ignition and replace it. 

This video shows possible reasons why a car won’t start when lights work.

3. Faulty Spark Plugs 

Spark plugs are responsible for igniting the car. However, they get dirty, break, or corrode, and the car will not start. If the lights on your dashboard are on and the radio is working, the spark plugs may be the problem.

Signs of faulty spark plugs.

  • You are using more fuel to cover the same distance. 
  • The car has been sluggish and doesn’t pick up speed when you accelerate. 
  • Engine misfires.
  • The engine is rough when idling. 

Check the spark plugs. If it is oily, clean it and then start the car. If the electrodes are broken or corroded, you need to replace the spark plugs. 

Read: How To Get Roaches Out of Car?

4. Gas Issues

Sometimes your car won’t start because the engine is not getting gas. This could be happening because the gas tank is empty, the gas line is frozen, or the fuel filter is clogged. 

If the gauge shows the tank is empty or you suspect you have no gas, you should refill the tank. 

If the temperatures have been low and you suspect a frozen gas line, you should thaw it. 

You can thaw the fuel line by:

  • Placing a portable heater under the car’s hood to warm the fuel line.
  • Get a fully charged battery to get the engine running. As the engine heats up, so will the fuel lines.
  • If the gas is less than half full, fill the tank. 
  • Use a thawing fuel additive.

Antifreeze can be an essential tool for this. I recommend checking out this ISO HEET Fuel Line Antifreeze (available on It absorbs up to 5 times more water from frozen gas lines than regular gas dryers, prevents corrosion, and removes water from the gas system. 

Read: What Cars Have Apple CarPlay?

5. A Damaged Fuel Pump

A fuel pump is essential for moving fuel from the tank to the carburetor. If it is spoiled, it will not move the fuel, and your car will not start. You need to have your mechanic look at the fuel pump since it is a sensitive part of the car, and the job may be complex. If the pump is damaged, you will need to get a new fuel pump.

6. Dirty Or Corroded Battery Terminals

Sometimes the problem with your battery is not necessarily the charge but poor connection due to dirty or corroded battery terminals. A battery with corroded terminals will not power the engine. Check the terminals for corrosion or dirt. 

If there are flaky white or blue substances at the terminals, you are dealing with corrosion. 

Read: Why Car Won’t Start With New Battery?

Solutions for a Car That Has Power but Won’t Start

If your car’s radio and lights come on, but the car fails to start, you shouldn’t attempt to force it to start. Instead, you should attempt to find the cause behind the problem. Attempts to force the car by turning the key multiple times may damage the starter. 

You shouldn’t overlook anything when trying to figure out why your car failed to start. Start with the more direct causes, such as a low battery, faulty spark plugs, and an empty gas tank. If they are all fine, you can proceed with more complex checks, such as the fuel filter, ignition, and battery terminals.

Here are some things you can do to fix this:

  1. Remove the negative terminal with a wrench. Ensure the wrench doesn’t contact the positive terminal, as you will get shocked.
  2. Disconnect the positive terminal.
  3. Check if the corroded terminals have warped the battery or caused cracks or dents. If the battery is damaged, cleaning the terminals will be of no use. You will need to replace the battery.
  4. If the battery is okay, pour a tablespoon of baking soda into a cup of hot water. Use an old brush to clean the corrosion using the mix. If the corrosion is extensive, use a battery terminal brush.
  5. Leave the battery to dry. Ensure the battery is completely dry before reassembling the battery. 
  6. Use the wrench to put back the terminals, starting with the positive one, followed by the negative terminal. 
  7. Start the engine. If the engine responds, you can drive your car, but take the car to your mechanic to have the battery tested. The battery may be working, but the corrosion may have shortened its lifespan. 

If you’re in need of a good wrench, I recommend this CRAFTSMAN Adjustable Wrench Set (available on It’s a pack of three wrenches that are corrosion-resistant, adjustable, and have large markings for easy size identification. They are versatile and can be used to open both narrow and wide jaws.

Read: Car AC Compressor Replacement Cost


There are multiple reasons why your car’s electrical components remain on when your car won’t come on. You will need to use elimination to determine what caused the problem and how to fix it. A faulty battery is often the problem, but your car may fail to start even when the battery is in great condition. If you are not confident about handling some parts of your car, it is best to have a professional check your car.

Leave a Comment