Fuel System:
* Empty fuel tank: Sounds obvious, but it's a frequent cause. Check your fuel gauge.
* Fuel pump failure: The pump may have stopped working, preventing fuel from reaching the engine. This can be intermittent.
* Clogged fuel filter: A dirty fuel filter restricts fuel flow.
* Bad fuel injectors: Injectors may be clogged or failing to deliver fuel properly.
* Fuel pressure issues: A leak in the fuel line or a faulty fuel pressure regulator can cause problems.
Ignition System:
* Dead battery: A weak or completely dead battery won't crank the engine. Check the battery voltage.
* Alternator failure: If the alternator stopped working, the battery may have drained.
* Faulty ignition switch: This switch controls the power to the ignition system.
* Ignition coil problems: The coil provides the high voltage needed for sparking.
* Spark plug issues: Worn, fouled, or damaged spark plugs prevent combustion.
* Distributor cap and rotor (older vehicles): These parts can wear out and cause ignition problems.
Other Potential Causes:
* Overheating: The engine may have overheated and triggered a safety shutdown. Check the coolant level.
* Sensor issues: Various sensors (crankshaft position sensor, camshaft position sensor, mass airflow sensor, etc.) monitor engine operation. A faulty sensor can prevent the engine from starting.
* Broken timing belt (or chain): This is a serious issue that can cause catastrophic engine damage. If the belt/chain broke while the engine was running, the engine likely needs major repairs.
* Computer/ECU problems: The engine control unit (ECU) could be malfunctioning.
What to do:
1. Check the obvious: Fuel level, battery voltage (use a voltmeter), and any warning lights on the dashboard.
2. Listen for unusual noises: Grinding, clicking, or unusual sounds can indicate specific problems.
3. Try again: Sometimes, a momentary electrical glitch causes the problem. Wait a few minutes and try again.
4. Call a tow truck or roadside assistance: If you can't identify the problem, it's best to have a professional diagnose and repair it. Don't attempt major repairs yourself unless you have the experience and tools.
Providing more details about what happened before the vehicle died (unusual sounds, smells, warning lights, etc.), the make, model, and year of the vehicle, and any attempts you've already made to restart it will help in narrowing down the possible causes.
