DTC 23

MAT Sensor Circuit:

Code 23 Wiring Diagram:

CIRCUIT DESCRIPTION:

The Manifold Air Temperature (MAT) sensor uses a thermistor to control the signal voltage at the ECM. The ECM applies a voltage (5.0 volts) on a GRAY wire to the sensor. When the air is cold, the sensor (thermistor) resistance is high, therefore, the ECM will see a high signal voltage. If the air is warm, the sensor resistance is low, therefore, the ECM will see a low voltage.

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

1. Code 23 will set if:

^ A signal voltage indicates a manifold air temperature below -48°C (-54.4°F) for 2.7 seconds. A Code 23 will set, due to an open sensor, wire, or connection. This test will determine if the wiring and ECM are OK.

2. If the resistance is greater than 25,000 OHMS, replace the sensor.

DIAGNOSTIC AIDS:

An intermittent may be caused by a poor connection rubbed through wire insulation or a wire broken inside the insulation. Inspect ECM harness connectors for backed out terminals "A13" or "A16," improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.