E074

Sensor Circuit:

DESCRIPTION:

This diagnostic test monitors manifold air temperature for a rapid change of 7 degrees or more in temperature in a short period of time. This code can be caused by an open, short to ground or short to voltage in CKT 472 and or 469. An open or short in the sensor connector, engine to dash connector or PCM/ECM connector. A defective sensor can also cause the code. This code will never set current, since it is set by a MAT sensor value which changes faster than what can occur in a normally operating system. This code indicates an intermittent signal fault which could cause a driveability symptom.

TEST CONDITIONS:

Engine running.

FAILURE CONDITIONS:

1. Manifold air temperature change of 7° or more in 250 milliseconds.

ACTION TAKEN:

1. Code set, no SERVICE ENGINE SOON lamp.

NOTE ON INTERMITTENTS:

Manipulate circuit 472 and 469 wiring, MAT sensor connector, engine to dash connector, and PCM/ECM connector while observing PCM/ECM data P.0.5. If a failure is induced the data will decrease and voltage will increase for an open circuit, or data will increase for data and voltage will decrease for a short to ground. Remove and reinstall the MAT sensor and PCM/ECM connectors to ensure that they are latched. Code snapshot data can provide comparative information if code E74 data is available. If wiring and connectors check out OK substitute a known good MAT sensor and retest.