Diagnostic Aids

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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.

CODE 13 ECM TERMINAL & CIRCUIT WIRING ID (ALL W/4L80-E A/T)

Application	ECM Terminal	Wire Color
O2 Sensor Signal	C14	Purple
O2 Sensor Ground	C13	Tan

CODE 13 ECM TERMINAL & CIRCUIT WIRING ID (ALL OTHERS)

Application	ECM Terminal	Wire Color
O2 Sensor Signal	D7	Purple
O2 Sensor Ground	D6	Tan

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

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

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