2.5L & 4.3L Turbo

1992 GMC Value Van 4.3 Z, AutomaticSECTION 2.5L & 4.3L Turbo

The ECM applies and monitors a voltage signal (4-6 volts) to MAT sensor. When manifold air is cold, the sensor resistance is high and ECM sees a high signal voltage. As air warms, resistance decreases and voltage sensed by the ECM drops. Sensor resistance can be measured at sensor terminals with harness disconnected.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This checks if the code is a hard failure or an intermittent condition. Code 25 will set if a VSS signal is present (2.5L) and monitored MAT sensor temperature is greater than 302°F (150°C) for 2.5L or 275°F (135°C) for 4.3L Turbo.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

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.