Diagnostic Aids

Verify a clean, tight connection for ground circuit No. 413. An open circuit at sensor signal terminal or ground terminal will result in a Code 13. Both oxygen sensor and heating element must be functioning properly to enable closed loop operation.

Fig 1: Code 13 Schematic (4.3L Turbo) Open Oxygen Sensor Circuit

Fig 2: Code 13 Flow Chart (4.3L Turbo) Open Oxygen Sensor Circuit