DTC 25

Fig. 010 - Chart - Code 25 Air Temperature Sensor (Signal Voltage Low):

Fig. 011 - WIRING DIAGRAM for Code 25 Air Temperature Sensor (Signal Voltage Low). VIN L:

CODE 25

AIR TEMPERATURE SENSOR (ATS)

SIGNAL VOLTAGE LOW)

3.0L "N" SERIES

FUEL INJECTION (PORT)

The Air Temperature Sensor uses a thermistor to control the signal-voltage to the ECM. The ECM applies a voltage (4-6) on CKT 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.
Code 25 will set if:
a. Signal voltage indicates a manifold air temperature greater than 135°C (275°F)
b. A vehicle speed signal is present.
c. Both of the above requirements are met for at least 30 seconds.
Due to the conditions necessary to set a Code 25 the check engine light will only remain on while the signal is low and vehicle speed is present.
1. If voltage is above 4 volts, the ECM and wiring are OK.
2. If the resistance is less than 100 ohms replace the sensor.