P0112
DTC P0112 Intake Air Temperature Circuit Low InputCIRCUIT DESCRIPTION
DTC Detection Condition:
The intake air temperature (IAT) sensor, mounted on the mass air flow (MAF) meter, monitors the intake air temperature. The IAT sensor has a thermistor that varies its resistance depending on the temperature of the intake air. When the air temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. The resistance varies as voltage changes to the ECM terminal. (See Fig. 1).
The intake air temperature sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the intake air temperature sensor from terminal THA (THAR) via resistor R.
That is, the resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes in accordance with changes in the intake air temperature, the potential at terminal THA (THAR) also changes. Based on this signal, the ECM increases the fuel injection volume to improve the driveability during cold engine operation.
HINT: After confirming DTC P0110, use the OBD II scan tool or hand-held tester to confirm the intake air temperature from the CURRENT DATA.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Component Operating Range:
The ECM monitors the sensor voltage and uses this value to calculate the intake air temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the IAT (Intake Air Temperature) sensor and sets a DTC.
Example:
When the sensor voltage output is equal to -40°C (-40°F), or more than 140°C (284°F).
Wiring Diagram:
INSPECTION PROCEDURE
Step 1:
Step 2:
Step 3:
Step 4 - 5:
HINT:
- If different DTCs related to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may be an open.
- Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, as well as other data from the time when a malfunction occurred.
CHECK FOR INTERMITTENT PROBLEMS
Hand-held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the ECM is in check mode with hand-held tester. In check mode, the ECM uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default), which uses 2 trip detection logic.
a. Clear the DTCs (see step 2).
b. Set the check mode (see step 3).
c. Perform a simulation test.
d. Check the connector and terminal.
e. Wiggle the harness and connector.