Possible causes fall into several broad categories:
* Engine Sensors: Failing oxygen sensors (O2 sensors), mass airflow sensors (MAF), throttle position sensors (TPS), crankshaft position sensors (CKP), or camshaft position sensors (CMP) are common culprits. These sensors send crucial information to the engine's computer, and a malfunctioning sensor can cause poor performance, rough idling, or even prevent the engine from starting.
* Emissions System: Problems with the catalytic converter, evaporative emission (EVAP) system, or other emission control components can trigger the light.
* Ignition System: Issues with spark plugs, wires, distributor cap, rotor, or ignition coil can cause misfires, leading to the Check Engine light.
* Fuel System: Problems with fuel injectors, fuel pump, or fuel pressure regulator can also set the light.
* Vacuum Leaks: A leak in the intake manifold or vacuum lines can disrupt engine operation and trigger the light.
* Other Issues: Less common issues such as a faulty coolant temperature sensor, transmission problems (though less likely to directly set the Check Engine light), or even a failing alternator can sometimes indirectly trigger it.
To diagnose the problem:
1. Get the trouble codes (if possible): While not as sophisticated as OBD-II, some 1995 models might have a simple diagnostic port. You'd need a code reader specifically designed for older vehicles (often called an OBD-I reader) to retrieve any stored codes. This is the most effective first step.
2. Visual Inspection: Check for obvious issues like loose vacuum hoses, damaged wires, or anything visually amiss under the hood.
3. Professional Diagnosis: Given the age of the vehicle and the limitations of OBD-I, taking it to a mechanic specializing in older vehicles is highly recommended. They have the tools and experience to properly diagnose the problem and repair it. They will likely use a scan tool specific to OBD-I or have the knowledge to use alternative diagnostic methods.
Don't ignore the Check Engine light. Continuing to drive with a problem can cause further damage and potentially lead to a more expensive repair.
