DTC 25

The Manifold Air Temperature Sensor uses a thermistor to control the signal-voltage to the ECM. The ECM applies a voltage (4-6V) on CKT 9 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:

^ Signal voltage indicates a manifold air temperature greater than 145°C (293°F).
^ Time since engine start is 2 minutes or longer.
^ Turbocharger wastegate control is not operated.

Due to the conditions necessary to set a Code 25, the "Check Engine" light will only remain on while the signal is low.

1. If voltage between ECM terminals M2-12 and M2-11 is above 4 volts, the ECM and wiring are OK.
2. If the resistance measured across the sensor terminals is less than 176 ohms, replace the sensor.