* Dead Battery: This is the most common reason. Check the battery terminals for corrosion and try jump-starting the car. If it starts, your battery needs replacing or charging.
* Alternator Problem: The alternator charges the battery while the engine is running. If it's faulty, the battery may drain, leaving you unable to start the car. You might notice dim headlights or other electrical issues before it completely dies.
* Starter Motor Issues: The starter motor is what cranks the engine to get it going. A faulty starter could be the culprit. You might hear a clicking sound when you turn the key but no engine cranking.
* Ignition Switch Problem: The ignition switch itself could be malfunctioning and not sending power to the starter.
* Security System Issues: If your Focus has a factory or aftermarket alarm or immobilizer system, it might be preventing the engine from starting. Try checking your key fob battery and making sure the system isn't triggered.
* Fuel System Problems: While less likely if it was running fine moments before, a fuel pump failure or a clogged fuel filter could prevent fuel from reaching the engine.
* Other Electrical Issues: A variety of other electrical problems could interrupt the starting process. This is a broad category that requires further investigation.
What to do next:
1. Check the obvious: Battery terminals, try jump starting.
2. Listen carefully: When you turn the key, do you hear any clicking, grinding, or other unusual noises? This can help pinpoint the problem area.
3. Check the fuel gauge: Is the fuel tank nearly empty?
4. Consult your owner's manual: It might provide troubleshooting tips.
5. Call a mechanic or tow truck: If you can't identify the problem yourself, it's best to get professional help to avoid further damage.
Providing more details about what happens when you turn the key (any sounds, lights flashing, etc.) will help narrow down the possibilities.
