Here's the proper approach:
1. Get the Diagnostic Trouble Code (DTC): This is crucial. You need to know *why* the check engine light is on. You have a couple of options:
* OBD-I Scanner: Your 1994 Mustang uses OBD-I, not OBD-II. You'll need an OBD-I scanner specifically designed for that year and model. These are often available at auto parts stores, or you can find them online. The scanner will read the code(s) stored by the car's computer.
* Auto Parts Store: Many auto parts stores offer free diagnostic code reading services. They can plug in a scanner and tell you the code(s).
2. Troubleshoot the Problem: Once you have the code(s), look up the meaning in a repair manual (Haynes or Chilton manuals are good options) or online (many resources exist for OBD-I codes). This will tell you what system is causing the problem (e.g., oxygen sensor, mass airflow sensor, etc.). You can then attempt to repair the issue yourself or take it to a mechanic.
3. Clear the Code (After Repair): *Only after you've fixed the problem*, you can clear the code. On many OBD-I systems, this involves:
* Disconnecting the Battery: Disconnect the negative (-) battery terminal for about 10-15 minutes. This will often clear the code. Reconnect the battery afterward.
* Jump Wire Method (Less Common & Riskier): Some OBD-I systems require jumping specific wires (consult a repair manual for your specific model). This is more complicated and could potentially damage your vehicle's computer if done incorrectly. Proceed with caution, if at all.
Important Considerations:
* Don't just clear the code without fixing the problem. This is a bad idea. Ignoring the issue can lead to further damage and potentially expensive repairs later.
* A repair manual is highly recommended. It will provide detailed information on troubleshooting and repair procedures specific to your 1994 Mustang.
* If you're not comfortable working on your car, take it to a qualified mechanic. They have the tools, knowledge, and experience to diagnose and repair the issue correctly.
In short: Diagnose the problem first, then fix it, *then* clear the code. Just clearing the code without fixing the underlying problem is like treating the symptom, not the disease.
