Here's a breakdown of possibilities:
* Loose or faulty gas cap: This is the simplest and cheapest thing to check first. A loose or damaged gas cap allows fuel vapors to escape into the atmosphere, triggering the check engine light. Tighten the gas cap securely. If it's cracked or damaged, replace it with a new, correct cap for your model. Drive for a few days and see if the light goes off. If it does, you're lucky!
* EVAP canister purge valve: This valve controls the flow of fuel vapors from the canister to the engine to be burned. A faulty purge valve can prevent proper vapor flow, leading to the check engine light. This requires more work – it's often located under the hood near the charcoal canister and may require a mechanic to diagnose and replace.
* EVAP canister: The canister itself stores fuel vapors. If it's cracked, damaged, or full of debris, it can malfunction, causing the light to illuminate. Replacing the canister is a more involved repair job.
* EVAP system hoses and lines: The EVAP system has a network of hoses and lines that can crack, become disconnected, or leak. These need to be inspected visually for any damage. Repairing these usually involves replacing the damaged hose or line.
* Other EVAP system components: There are other sensors and components within the EVAP system that could fail (e.g., vapor pressure sensor). Diagnosis of these requires a scan tool that can read the specific trouble code (DTC) stored in the car's computer. The code will point you to the specific faulty component.
What you should do:
1. Tighten the gas cap: This is the first and easiest step.
2. Get the trouble code read: Use an OBD-II scanner (available at most auto parts stores) to read the Diagnostic Trouble Code (DTC). This code will pinpoint the problem far more accurately than guesswork.
3. Consult a repair manual: A repair manual specific to your 2000 Chevy Cavalier will provide diagrams of the EVAP system and troubleshooting steps.
4. Take it to a mechanic: If you're uncomfortable working on your car yourself, take it to a qualified mechanic. They can diagnose the problem accurately and perform the necessary repairs.
Ignoring the check engine light can lead to further problems and potentially damage your vehicle's emission system. Addressing this issue promptly is recommended.
