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Code 13 - Open O2 Sensor Circuit

NOTE: If Codes 13 and 23 exist, start with Code 23.

NOTE: Test numbers refer to test numbers on diagnostic chart.

This step checks if ECM can respond to lean O2 sensor signal (low voltage).
This step determines if there is an open O2 sensor wire or faulty ECM.
This step checks for bad ground to ECM.

Fig 1: Chart 13 - Schematic

Courtesy of ISUZU MOTOR CO.

Fig 2: Chart 13 - Diagnostic Flowchart

Courtesy of ISUZU MOTOR CO.