Why a car won't start troubleshooting tips.

Updated: August 13, 2013
Car won't start

It is frustrating when your car won't start. You are turning the key and... nothing happens. Almost every car owner has experienced this.
There are many things that can go wrong with your car, but no need to worry, there is a solution for almost every problem.
Of course, you can call your local automobile association or a towing service and have your car towed to a local repair shop, but if you want to know why it doesn't start, read further.
The process that goes on from the moment you put the key into the ignition to the point where the engine is running involves a few steps. Once you know at which step things go wrong, you will have a better idea why your car won't start and what to do.
Answer these questions; if the answer has a link, follow it; if not, continue to the next questions.


What happens when you are trying to start the engine?

Ignition ON

1. Can you turn the key in the ignition? Yes No
2. When you turn the ignition ON:
Do the lights come on in the instrument panel?
Yes No
Does the "Security" or Key-shaped light stays on or flashes in the instrument panel? Yes No
Does the "Check engine" light come on? Yes No
3. What happens when you turn the ignition key to the "Start" position?
- Nothing happens, the engine won't turn over.
- There is a click (or repeated clicking) but the engine won't turn over.
- The engine turns over (cranks) very slowly.
- The engine cranks progressively slower, then just clicks.

If the starter cranks normally, but the car won't start continue to the

What to check first

If the car won't start, check the basic things first:
Is the battery OK? Read the next paragraph how to check the battery.
If the car doesn't start with the automatic transmission in "Park," does it start in "Neutral"? Sometimes a car won't start in "Park" but starts in "Neutral" because of a problem with a neutral safety switch. Read more about neutral safety switch here: how a car starting system works.
Are the battery cables tight and not corroded?
Do you think Is there enough fuel in the tank? It's a common situation when the fuel gauge isn't working properly and the car runs out of fuel with the fuel gauge still showing some fuel left. There is no way to check the fuel level other that the fuel gauge. But you can estimate how long did you drive since the last fill up. Read also about signs of low fuel level on the second page of this guide.
Is the "Security" or key-shaped light in the instrument panel stays on or blinking? Read below about the security light.
Does your car have an anti-theft system that for some reason doesn't allow the car to be started?

How to check the battery

A discharged or dead battery is one of the possible reasons for a car not to start. Sometimes we just forget to turn off the dome light or something else, or it could be some faulty component of the vehicle electrical system that drains the battery down. Sometimes, if the battery is old, it could just die one day, even if the day before it was OK. In either case, if the battery is low on charge, it won't have enough power to turn over the engine: you may hear some clicking noise or the starter may turn very slow when attempting to start the engine.

Here is a simple way to check if the battery is discharged:
Turn the windshield wipers on. If they move very slow, much slower than usual, the battery is probably low on charge. Look at the dome light. Does If it gets very dim when you try to start or when you turn the wipers on, the battery is most likely discharged.

If the battery is relatively new, it can be recharged. One way to do this is to jump start your car and let the engine run for a while to re-charge the battery. Read below about jump starting. One thing to be aware: if the battery is more than 4-5 years old, it might be completely dead, so it won't take charge and the car will not restart again after you shut it off. In this case, you may need a new battery. A problem with the vehicle's charging system can also cause the battery not to re-charge.

The key won't turn in the ignition

If the key won't turn in the ignition, it could be for a couple of reasons: Often this happens when the steering is locked by the ignition lock with the front wheels turned aside (e.g. when parking on a hill) or when one of the front wheels is pushed against something (e.g. curb stone). In this case, try turning the steering wheel left and right while gently jiggling the ignition key - this might help to release the steering lock.
Another possibility is that there is a problem with the ignition lock or the key itself. This happens; the key and the lock mechanism wear over time. Try to use a spare key. If nothing works, your local dealer is the best place to call.

No lights on the instrument panel

If you turn the ignition on and no lights come on at the instrument panel means that there is no power coming from the battery. It could be a dead battery or often a bad ignition switch could cause this. Turn the headlights on, if they work, means the battery has power, so the problem could be with the ignition switch or wiring between the ignition switch and battery.

If no lights coming on in the dash and no other electrical consumers work, the battery could be completely dead or there is no connection between the battery and the vehicle electrical system. Check if the battery terminals look tight. If the battery is completely dead, jump starting might help.

"Security" or Key-shaped light stays on or flashes on the dashboard

Security light flashing

Many cars are equipped with an immobilizer or a security system that allows the engine to start only if the correct key is used. You can find more information about the immobilizer in your owner's manual.
Basically it means that an ignition key has a chip inside with the security code. When you insert it into the ignition, a sensor for the security system reads the code. Normally when you turn the ignition on, you would see a "Security" light to come on for a short time and then it would come off. That would mean that the code in the ignition key is correct and the car is allowed to start.

If when you turn the ignition ON, the "Security" light stays on or flashing means that your car security system does not recognize the key or there is some problem with some part of the security system itself.
Some GM cars, for example, had a problem with the security system sensor located at the ignition lock. Sometimes, the key is just need to be reprogrammed. You can find the information how to re-program the key in your owner's manual or just Google it. In some cases there is a simple procedure to re-learn the key that fixes this problem. You also can try the spare key and if nothing works, your dealer is the place to call. You dealer can check your immobilizer and reprogram the ignition keys if needed.

The "check engine" light does not come on

Check Engine Light

When you turn the ignition ON before starting the car, the "Check engine" light is supposed to come on indicating that the engine computer (also could be called ECM, PCM, or ECU) is powered on. If the "Check engine" light does not come with the ignition ON, it's possible that there is no power coming to the engine computer (e.g., due to a broken wire, faulty main relay, burnt fuse, etc.) or that there is a problem with the engine computer itself.

The starter won't crank

If nothing happens when you turn the ignition key to the "Start" position, it means that the starter motor doesn't turn over the engine. Most commonly this could be caused by a dead battery; here is How to check the battery.
If the battery checks out OK, but the starter still won't crank, there could be a number of possible reasons. Here are some of them:

The ignition switch could be bad - it's a common problem. An ignition switch is an electrical switch installed at the back of the ignition lock mechanism. If jiggling the key in the ignition helps start the car, the ignition switch should be checked first.
The starter solenoid control wire could have a bad connection.
The starter motor itself or a starter solenoid could be bad.
A neutral safety switch is bad. If a car doesn't start with the transmission in Park, but starts in Neutral, it could be caused by a problem with a neutral safety switch.
Read more about starting system.
A problem with vehicle's security system or some other electronic control module (e.g., ECM, BCM) may also prevent the starter from operating.

I can hear a click, but the starter won't crank

It's a very common problem: you turn the key to the "Start" position, but the engine won't crank; all you hear is a single click or repeated clicking coming from the engine compartment. This has happened to me many times. Very often this could be caused by a weak battery or poor connection at the battery terminals. Sometimes a battery cable can get corroded inside causing the same problem. In some cases a bad connection between the negative battery cable and the engine (bad ground) can cause the same symptoms.
Of course, there could be other reasons, but most often this happens when there is not enough electric current for the starter motor to turn over the engine.
See this paragraph: how to check the battery.
Also, check the battery terminals to make sure they are not corroded. Here is a photo how a corroded battery terminal looks: Car maintenance checklist: Battery
If the battery is OK and the battery terminals appear clean and not corroded, the starter solenoid, battery cables or the starter motor itself could be a problem. For example, a problem with the starter motor or solenoid is a fairly common cause for the 2000-2006 Ford Taurus not to start. Earlier models of this vehicle had some problems with starters too. A similar problem with the starter solenoid in 1998-2002 Toyota Corolla sometimes can also cause a condition when there is a click but the starter won't crank. Similarly, in 1998-2001 Toyota Camry a problem with the starter solenoid terminals could cause the condition where the starter would click, but would not crank. In either case the starter motor needs to be rebuilt. Read more here: Starter motor, starting system.

The engine cranks very slow and won't start

This also might be caused by weak or discharged battery; here is how to check the battery. If the battery is OK, the battery cables could have a bad connection at the terminals or the starter motor itself could have a problem. Sometimes, the starter motor armature bushings wear out and the starter armature rubs against the field coils inside the starter motor; this will also cause the starter motor to crank very slow. If this is the case, the starter motor will need to be rebuilt or replaced. Another reason, the engine could have an internal mechanical problem (e.g., lack of oil, very old engine oil, etc.). Check engine oil, just in case. Read here how to check engine oil.

The engine cranks progressively slower, then just clicks

If the engine cranks slower and slower until it just clicks, means the starter motor doesn't have enough power to turn over the engine. This problem should be fairly easy to diagnose, as there are just two cables (positive and negative) to deliver the electric current from the battery to the starter motor. Once again, a very weak battery is the most common problem in this case. A bad starter motor also can cause this issue. And of course, a poor connection or corrosion at the battery terminals or bad battery cables can also cause these symptoms. If the battery is very old, you might want to start with replacing the battery; a new battery is not very expensive.

Jump-starting a car

A jump start is a way of starting a car with a weak battery using a power from a good battery in another vehicle. You will need jumper cables and another car with a good battery, and it's a fairly quick procedure. Last time my battery died at a grocery store parking lot, a fellow driver helped me to jump start my car from his vehicle - luckily, I had the jumper cables. We connected the cables, my engine started right away, and in a couple of minutes I was on my way to the parts store to get a new battery.
Now, the process is simple, but you should check your owner's manual for the right way to do this in your vehicle, because different cars have different locations of the connection points. It's important to connect the jumper cables the right way, so check the instructions in your owner's manual carefully. If you don't have an owner's manual, many car manufacturers offer to download an electronic copy from their websites. Read here: Where to download an owner's manual
Be careful, a person I know had to scrap his car after he accidentally mixed the positive and negative cables while jump-starting his car; this caused extensive damage to his vehicle's electrical system.