"Hard Failures"

When system failures occur, "CHECK ENGINE" light illuminates. This function, termed the "U-check" mode, monitors only the MPFI components necessary for start-up and drive. This is a continuous system function for the purpose of alerting the vehicle operator of a needed repair.

"D-check" mode diagnoses entire MPFI system. In "D-check" mode, problem related trouble code(s) are displayed by O2 monitor light. See Figure or Figure . The code(s) remain accessible until malfunction is repaired. Malfunction is determined using diagnostic (code) charts. If more than one code is present, the lowest number trouble code is to be diagnosed first.