Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1988SPECTRUM BASE, 2D HATCHBACK, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEM1.5L EFI TURBOTROUBLE SHOOTINGCOMPONENT TESTING BY TROUBLE CODECODE 23 & 25 (MAT)
1988 Chevrolet Spectrum Base, 2D Hatchback, Automatic
Code 23 & 25 (MAT)
1988 Chevrolet Spectrum Base, 2D Hatchback, AutomaticSECTION Code 23 & 25 (MAT)
- Clear codes. Start engine and run for one minute or until light comes on. Turn engine off and turn ignition on. Note codes.
- If code 23 is present, disconnect MAT sensor harness. Turn ignition on and check voltage between MAT sensor harness terminals. If voltage is below 4 volts, check voltage between MAT Black/Yellow harness connector and ground.
- If voltage check is below 4 volts, check for open in harness, faulty connection or ECM. If voltage in Black/Yellow wire is over 4 volts, check for faulty circuit in Red/Black wire to ECM harness connector A11.
- If reading across harness terminals in step 2) was over 4 volts, check resistance across MAT sensor terminals. See MAT SENSOR RESISTANCE table. If resistance values are not approximately as indicated, replace MAT sensor.
MAT SENSOR RESISTANCE
| Temperature | Ohms |
|---|---|
| -4°F (-20°C) | 28,677 |
| 32°F (0°C) | 9423 |
| 68°F (20°C) | 3515 |
| 104°F (40°C) | 1459 |
| 140°F (60°C) | 667 |
| 176°F (80°C) | 332 |
| 212°F (100°C) | 177 |
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.