Common Causes in a 2000 Dodge Neon:
* Oxygen Sensor (O2 Sensor): These sensors monitor the air/fuel mixture. A faulty sensor will throw a code and negatively impact fuel economy and emissions. This is a very common culprit in older vehicles.
* Mass Airflow Sensor (MAF Sensor): Measures the amount of air entering the engine. A dirty or faulty MAF sensor can lead to a rich or lean fuel mixture, affecting performance and triggering the light.
* Catalytic Converter: If this is failing, it can cause a variety of issues and trigger the check engine light. This is an expensive repair.
* Spark Plugs and Wires: Worn-out spark plugs or damaged ignition wires can cause misfires, leading to the light illuminating.
* PCV Valve (Positive Crankcase Ventilation): A malfunctioning PCV valve can cause excessive pressure buildup in the crankcase, leading to oil leaks and affecting engine performance.
* Throttle Position Sensor (TPS): This sensor tells the engine control unit (ECU) the throttle's position. A faulty TPS can cause poor idle, stalling, and trigger the check engine light.
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the ECU the position of the crankshaft. A faulty CKP sensor can prevent the engine from starting or running smoothly.
Less Common (but still possible):
* Issues with the fuel system: Fuel pump, fuel injectors, fuel pressure regulator.
* Problems with the emissions system: EGR valve, evaporative emission system.
* Sensor wiring or connectors: Corrosion or damage to wiring harnesses can lead to false readings.
How to Diagnose:
1. Get the Diagnostic Trouble Codes (DTCs): You'll need an OBD-II scanner (available at auto parts stores for relatively inexpensive prices). Plug it in, and it will read the trouble codes stored by the car's computer. These codes will give you a much better idea of the specific problem.
2. Research the Codes: Once you have the codes, look them up online (many free resources are available). This will help you narrow down the possible causes.
3. Visual Inspection: Check for obvious problems like loose or damaged wires, vacuum leaks, or anything out of the ordinary.
4. Professional Diagnosis (if needed): If you're not comfortable diagnosing and repairing the issue yourself, take your Neon to a mechanic. They have the tools and expertise to properly diagnose and fix the problem.
Ignoring the check engine light is not recommended. Continuing to drive with a problem can lead to more severe damage and costly repairs down the line.
