Car won't start? What the signs tell you
By LSG Auto Nation · · Updated
Short answer
Notice what the car does when you try to start it. Fast clicking or a slow, tired start usually means a weak battery or a loose battery cable. One loud click points to the starter. If the engine turns over normally but won't run, the problem is usually fuel, spark or a sensor. A mechanic will need to test it.
A car that won’t start is stressful. The good news is that what it does when you turn the key or press the start button tells you a lot about what’s wrong.
What do the different signs mean?
| What happens | Likely cause | What to do |
|---|---|---|
| Nothing at all, no lights | A flat battery, or a loose or dirty battery cable | Check the battery cables, then try a boost |
| Fast clicking | The battery is too weak to start the engine | Boost it, then get the battery tested |
| One loud click, lights stay bright | The starter, the motor that turns the engine over | Get the starter tested |
| Slow, tired starting | A weak battery, often in cold weather | Get the battery and charging tested |
| Engine turns over but won’t run | A fuel, spark or sensor problem | Book a diagnostic check |
| Starts, then dies right away | A fuel, air, sensor or anti-theft problem | Book a diagnostic check |
What can I check myself first?
- Is the car in Park? Most cars won’t start in Drive. In a manual, push the clutch all the way down.
- Do the dashboard lights come on? If nothing lights up, the battery or its cables are the likely problem.
- Are the battery cables tight and clean? White or green crusty build-up can stop power getting through.
- Is there gas in the tank? Fuel gauges do sometimes fail.
- Is a key or security light flashing? The car may not recognize your key. Try the spare.
If you boost the car, follow the steps in your owner’s manual and connect the cables in the right order.
When should I call a mechanic?
Call a shop if:
- the car still won’t start after a boost
- it needs a boost more than once
- the engine turns over but never runs
- you smell gas
Trying to start it again and again can damage the starter, and replacing parts on a guess gets expensive fast.
At the shop, we test things in order: first the battery, then the starter and the charging system. If the engine turns over but won’t run, a diagnostic check tests the fuel, spark and sensors.