Why a car won't start
Troubleshooting tips. Part 1

It's frustrating when your car won't start - this has happened at least once to most of the drivers. I myself had situations when my car would just decide to call in sick and wouldn't start many times. You are turning the key and... nothing happens. There are many things that can go wrong, but no need to panic, there is a solution for practically every problem, it's just not always easy to find. Hopefully, this article will help you to find out why your car won't start, and if not, this information will help you to better explain your problem to a mechanic. A very detailed description will help your mechanic to diagnose the problem quicker.

What happens when you are trying to start the engine?

Ignition is ON

The process that goes on since 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.
Let's start with a few questions to find out at which step things go wrong. Your mechanic may ask you similar questions; this may help him (her) find the problem easier. If the answer has a link, follow it; if not, continue to the next questions.

Can you turn the key in the ignition? .................................. Yes No
When you turn the ignition ON before starting the car, do the lights come on in the
instrument panel? ............................................................... Yes No
When you turn the ignition ON before starting the car, does the "Security" or Key-shaped
light stays on or flashes in the instrument panel? ................... Yes No
When you turn the ignition ON before starting the car, does the "Check engine" light
come on? ........................................................................... Yes No
What better describes your situation when you turn the ignition key to "Start" position?
Nothing happens, the starter won't crank.
There is a click (or repeated clicking) but the starter won't crank.
The starter cranks very slowly.
If the starter cranks normally, but the car won't start continue to the next page »
If you are interested to know more technical details about the process involved in starting a car's engine with the illustrations, read here: How a car starts - step by step.

What to check first

If the car won't start, check the basic things first:
Is the battery OK? Read the next paragraph for a simple way to check 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?
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 in the tank. Check 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 slowly when attempting to start the engine.
Here is a simple way to check if the battery is discharged:
Turn the ignition on. Without starting the engine, turn the windshield wipers on. If they move way too slow, much slower than usual, the battery is probably 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 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.
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. You can try to jump start your car; if it's a dead battery, jump starting can help.

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

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 code in it and 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. I know that in some cases there is a simple procedure to re-learn the key that fixes this problem. You also can try a 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

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 to start the car, the ignition switch should be checked first.
- The starter motor itself or a starter solenoid could be bad.
- A starter solenoid control wire could have a bad connection.
- 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 and neutral safety switch.
- A problem with vehicle's security system or some other electronic control module (e.g., PCM, 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.
Read the paragraph above: 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. In either case the starter motor needs to be rebuilt.
Read more here: Starter motor, starting system.

The starter cranks very slowly, the engine 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, battery cables could have a bad connection or the starter motor itself could have a problem. Another reason, the engine could have an internal mechanical problem (e.g., lack of oil, very old engine oil, etc.).

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.

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