Daewoo MATIZ Service Manual page 164

1F – 66 ENGINE CONTROLS
DIAGNOSTIC TROUBLE CODE (DTC) – P0112 INTAKE AIR TEMPERATURE
Circuit Description
The Intake Air Temperature (IAT) Sensor uses a therm-
istor to control the signal voltage to the engine control
module (ECM). The ECM supplies a 5 volt reference
voltage and a ground to the sensor. When the air is cold,
the resistance is high ; therefore IAT sensor signal volt-
age will be high. If the intake air is warm, resistance is
low ; therefore the IAT sensor signal voltage will be low.
Conditions for Setting the DTC
D The engine rum time is greater than 3 seconds.
D IAT voltage is less than 0.01V
Action Taken when the DTC Sets
D Emission related.
D "Armed" after two trip with a fail.
D "Disarmed" after one trip with a pass.
D MIL on if failure is detected in three consecutive trips.
D Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).
SENSOR LOW VOLTAGE
D Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).
D The ECM will default to 60°C(140°F)for intake air
temperature. The scan tool will not show the de-
faulted value.
Conditions for Clearing the MIL/DTC
D The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
D A history DTC will clear after 40 consecutive warm up
cycles without a fault.
D DTC(s) can be cleared by using the scan tool.
Diagnostic aids
If the vehicle is at ambient temperature, compare the
IAT sensor to the engine coolant temperature(ECT) sen-
sor. The IAT sensor and the ECT sensor should be rela-
tively close to each other. Use the temperature vs.
Resistance Values table to evaluate the possibility of a
skewed sensor. Refer to "Temperature vs. Resistance"
in this Section.
MAA1F100
DAEWOO M-150 BL2