Most Likely:
* Fuel System Issues:
* Low fuel: The most obvious! Check your fuel gauge.
* Fuel pump: A failing fuel pump might provide enough fuel for initial startup but not sustain it at idle. Listen for the hum of the fuel pump when you turn the key to the "on" position (before starting). A weak hum or no hum is a bad sign.
* Clogged fuel filter: A dirty fuel filter restricts fuel flow, leading to problems at idle when fuel demand is relatively low.
* Fuel injectors: Clogged or faulty injectors can't deliver enough fuel consistently.
* Fuel pressure regulator: A faulty regulator might not maintain proper fuel pressure.
* Ignition System Issues:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position. A faulty one can lead to the engine stalling, especially at idle.
* Cam Position Sensor (CMP): Similar to the CKP, a bad CMP sensor can cause the engine to die.
* Ignition coil(s): A failing coil might not provide sufficient spark consistently, especially under lower engine loads (idle).
* Spark plugs/wires: Worn spark plugs or damaged wires can lead to misfires, eventually causing a stall.
* Air Intake System:
* Mass Airflow Sensor (MAF) Sensor: A dirty or faulty MAF sensor provides incorrect information to the engine computer about the amount of air entering the engine, leading to a lean condition and stalling.
* Vacuum leak: A leak in the intake system can disrupt the air/fuel mixture.
Less Likely (but still possible):
* Cooling System Issues: Overheating can cause the engine to shut down as a safety precaution. Check your coolant level.
* Alternator: A failing alternator won't charge the battery, and eventually the car will die. Check your battery voltage.
* Throttle Body: A dirty or faulty throttle body can affect idle control.
* Computer/ECU issues: While less common, a problem with the Engine Control Unit (ECU) can cause erratic behavior and stalling.
Troubleshooting Steps:
1. Check the obvious: Fuel level, coolant level, battery voltage.
2. Listen for unusual sounds: A ticking, whining, or clicking sound could indicate a specific component failing.
3. Check engine codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the car's computer. These codes can provide valuable clues.
4. Inspect visually: Look for any obvious damage to wiring, hoses, or components.
5. Start with the most likely suspects: Focus on the fuel system and ignition system first.
If you're not comfortable working on your car yourself, take it to a qualified mechanic for diagnosis and repair. Trying to diagnose this problem without the proper tools and knowledge could lead to further damage. Providing the year, make, and model of your car will help narrow down the possibilities.
