Code 23: Mat Sensor CKT-Low Temp Indicated (Turbo): Notes
The MAT sensor uses a thermistor to control signal voltage to the ECM. The ECM applies 4-6 volts on Blue/Black wire to MAT sensor. When manifold air is cold, sensor resistance is high and ECM will see a high voltage. As air temperature increases, sensor resistance decreases and the voltage drops.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This determines if Code 23 is result of a hard failure or an intermittent condition. Code 23 will set if engine is running longer than 1 minute and signal voltage indicates a MAT temperature below -38°F (-39°C).
- This step simulates conditions for a Code 25. If Scan tester displays a high temperature, ECM and wiring are okay.
- This step checks continuity of Blue/Black wire and Black/White wire. If Black/White wire is open, a Code 22 may be present.