Diagnostic Aids

1995 Chevrolet Forward Control 4.3 Z, AutomaticSECTION Diagnostic Aids

Verify a clean, tight connection for sensor ground. An open circuit at sensor signal terminal or ground terminal will result in a Code 13.

CODE 13 TERMINAL & CIRCUIT WIRING IDENTIFICATION

Engine Application ECM/PCM Terminal Wire Color
"C" & "K" Series
7.4L
Oxygen Sensor Signal A10 Purple
Oxygen Sensor Ground A12 Tan
"G" Series
7.4L A/T
Oxygen Sensor Signal A10 Purple
Oxygen Sensor Ground A12 Tan
"P" Series
7.4L A/T
Oxygen Sensor Signal A10 Purple
Oxygen Sensor Ground A12 Tan
Fig 1: Code 13 Schematic (All Models) Open Oxygen Sensor Circuit
G91H07378
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.