Here's what you should do:
1. Get the Diagnostic Trouble Codes (DTCs) read: This is crucial. You can't effectively diagnose the problem without knowing the specific code(s) the computer has logged. You can do this in a few ways:
* Auto parts store: Most auto parts stores will read the codes for free.
* OBD-II scanner: Buy a relatively inexpensive OBD-II scanner. This allows you to read and clear codes yourself, which is handy for future issues.
* Mechanic: A mechanic will be able to read the codes and diagnose the problem.
2. Interpret the DTCs: Once you have the codes, look them up online (there are many resources, including repair manuals specific to your 1997 Cavalier). This will give you a much clearer indication of the potential problem.
3. Possible causes (besides a faulty EGR): Even if the EGR valve itself *seems* okay, other components in the system could be malfunctioning, leading to the check engine light. These include:
* EGR valve position sensor: This sensor monitors the EGR valve's position and can throw a code if it's malfunctioning.
* Vacuum lines: Leaky or disconnected vacuum lines to the EGR valve are common culprits.
* EGR temperature sensor: A faulty sensor can cause incorrect readings and trigger a code.
* Other engine-related issues: The check engine light is a general indicator. The problem could be completely unrelated to the EGR system (e.g., oxygen sensor, mass airflow sensor, catalytic converter, etc.).
In short: Don't assume it's the EGR just because it *appears* fine. Get those codes read first! That's the only way to accurately diagnose and fix the problem.
