Sonata V6-3.0L (1991)
ECU System
NOTE: In the event of a recurring check engine light accompanied by an oxygen sensor fault code, the probable cause is a poor alternator to engine
ground, and excessive resistance in the battery ground circuit. For the recommended correction refer to TSB# ENG016.
To test the Check Engine Light, located in the instrument cluster, turn the ignition switch on. The light should illuminate. This insures that the light is
operative. If the light bulb does not illuminate the most likely fault is a defective light bulb. If the light tests good the other possible causes are, the ECU
not supplying power (check pin #14 of ECU connector C02-2), the wiring harness or instrument cluster printed circuit board (refer to ELECTRICAL
AND ELECTRONIC DIAGRAMS).
