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DTC P0112: Intake Air Temperature Circuit Low Input
 
 
 
 
CIRCUIT OPERATION
  • Approximately 5 volts are applied to the intake air temperature sensor output terminal from the ECM terminal ATS via the resistor in the ECM. The ground terminal is grounded with ECM terminal AFSE.
  • The intake air temperature sensor is a negative temperature coefficient type of resistor. When the intake air temperature rises, the resistance decreases.
  • The intake air temperature sensor output voltage increases when the resistance increases and decreases when the resistance decreases.
 
 
TECHNICAL DESCRIPTION
  • The intake air temperature sensor converts the intake air temperature to a voltage.
  • The ECM checks whether this voltage is within a specified range.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • Intake air temperature sensor output voltage is out of specified range.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
Check Condition
  • More than 2 seconds have passed since the power supply mode of the electric motor switch was ON.
or
  • More than 2 seconds have passed since the key-off evaporative leakage monitoring was started.
Judgment Criterion
  • Intake air temperature sensor output voltage has continued to be lower than 0.2 volt [corresponding to an intake air temperature of 115°C (239°F) or higher] for 2 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Control as if the intake air temperature is 25°C (77°F).
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Intake air temperature sensor failed.
  • Shorted intake air temperature sensor circuit, or connector damage.
  • ECM failed.

 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), check data list item 5: Intake Air Temperature Sensor.
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Turn on the power supply mode of the electric motor switch.
(3) Set scan tool (M.U.T.-IIISE) to the data reading mode for item 5, Intake Air Temperature Sensor.
  • The intake air temperature and temperature shown with the scan tool should approximately match.
(4) Turn off the power supply mode of the electric motor switch.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Go to Step 2.
 
STEP 2. Check the intake air temperature sensor.
Refer to Intake Air Temperature Sensor Check .
Is the measured resistance at the standard value?
Go to Step 3.
Replace the mass airflow sensor. Then go to Step 5.
 
STEP 3. Check of short circuit to ground in ATS line between mass airflow sensor connector and ECM connector.
Is the harness wire in good condition?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 4.
Repair the connector(s) or wiring harness. Then go to Step 5.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check data list item 5: Intake Air Temperature Sensor.
(1) Turn on the power supply mode of the electric motor switch.
(2) Set scan tool (M.U.T.-IIISE) to the data reading mode for item 5, Intake Air Temperature Sensor.
  • The intake air temperature and temperature shown with the scan tool should approximately match.
(3) Turn off the power supply mode of the electric motor switch.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Replace the ECM (Refer to Removal and Installation ). Then go to Step 5.
 
STEP 5. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0112 set?
Retry the troubleshooting.
The inspection is complete.