Code 23 Mat Sensor Temp. Low - 1992 2.5L & 4.3L Turbo: Notes

Fig 1: Code 23, MAT Sensor Temp. Low Circuit Diagram (1992 2.5L & 4.3L Turbo)

Courtesy of GENERAL MOTORS CORP.

NOTE: Test numbers refer to test numbers in diagnostic chart.

1. This step will determine if Code 23 is the result of a hard failure or an intermittent condition. Code 23 will set if a signal voltage indicates a intake air temperature below minus 22 degrees for 12 seconds, time since engine start is one minute or longer or no vehicle speed signal present.
2. Code 23 will set due to an open sensor, wire or connection. This test will determine if wiring and ECM are okay.
3. This test will determine if signal from circuit No. 472 or the 5 volt return in circuit No. 469/452 is open.