DTC 23

Code 23 Chart:

Manifold Air Temperature Sensor Wiring Diagram:

CIRCUIT DESCRIPTION:

The Manifold Air Temperature (MAT) sensor uses a thermistor to control the signal-voltage to the ECM. The ECM applies a voltage (4-6V) on circuit 472 to the sensor. When manifold air is cold, the sensor (thermistor) resistance is high, therefore, the ECM will see a high signal voltage. As the air warms, the sensor resistance becomes less, and the voltage drops.

TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. A Code 23 will set if:

a. Signal voltage indicates a manifold air temperature greater than 150°C (302°F) for 2 seconds.
b. Time since engine start is 1 minute or longer.
c. No Vehicle Speed Sensor (VSS) signal.

2. If the resistance is less than 100 Ohms, replace the sensor.