Code 23, Intake Air Temperature Low: Notes

Control module supplies and monitors a voltage signal (4-6 volts) to sensor. When temperatures are low, sensor resistance is high and control module will see a high-monitored voltage signal. As temperature increases, sensor resistance decreases and voltage sensed by control module drops.

1. This checks if Code 23 is a hard failure or an intermittent condition.
2. This simulates conditions for a Code 25. If scan tester displays a high temperature, control module and wiring are not at fault.
3. This checks for continuity of sensor signal and ground circuits.