Check Engine Lights for Model Years Up to 1995

Emissions Malfunction Lights

The emissions malfunction indicator on most vehicle models prior to 1996 is based on the first generation of On-Board Diagnostics, known as OBD I. The malfunction light is known on some models as the Check Engine, Power Loss, Service Engine Now or Service Engine Soon light. This light is intended to alert the operator when there is a failure in the system that may cause an increase of harmful emissions.

If Your Check Engine Light is On

The check engine light illuminates when the ignition key is in the on position and the engine is off; this is to functionally test the system and check the bulb. When the light turns on during engine operation, even momentarily, a system diagnosis is necessary to determine the fault. When the light is on steady, it means there is a fault currently detected.

If Your Check Engine Light is On Intermittently

If the check engine light illuminates, and then turns off, it can mean that the fault is intermittent or that the fault is only being detected intermittently. In either case, if the light is intermittent it usually means the technician will have to try to recreate the operating conditions under which the light illuminates in order to diagnose the problem.

Avoid Vehicle Damage with Warning Light Diagnosis

Diagnosis of an intermittent problem is more difficult, sometimes a hit or miss situation, and sometimes requires bringing the vehicle in several times before the fault is located. Although this warning light’s purpose is to warn of increased emissions, in most cases if the system is not promptly repaired, damage to other components can occur.

For later model vehicles check out Check Engine Lights for Model Years 1996 to Present