2.5L & 4.3L Turbo

1992 GMC Magnavan 5.7 KSECTION 2.5L & 4.3L Turbo

The ECM supplies and monitors a voltage signal (4-6 volts) to the sensor. When temperatures are low, sensor resistance is high and the ECM will see a high-monitored voltage signal. As temperature increases, sensor resistance decreases and voltage sensed by the ECM drops.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This checks if Code 23 is a hard failure or an intermittent condition. Code 23 will set if engine is running for one minute, MAT sensor temperature is less than -22°F (-30°C) for 12 seconds and speed sensor signal is not present.
  2. This simulates conditions for a Code 25. If the Scan tester displays a high temperature, the ECM and wiring are not at fault.
  3. This checks for continuity of sensor signal and ground circuits.
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.