P0112

DTC P0112: Intake air temperature Circuit Low Input

Intake Air Temperature Sensor Circuit:

CIRCUIT OPERATION
- Approximately 5 volts are applied to the intake air temperature sensor output terminal (terminal No. 6) from the ECM (terminal No.72) via the resistor in the ECM. The ground terminal (terminal No. 5) is grounded with ECM (terminal No. 40).
- 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 stored in memory for the item monitored)
- Not applicable

Sensor (The sensor is determined to be normal)
- Not applicable

DTC SET CONDITIONS

Logic Flow Chart:

Logic Flow Chart

Check Conditions
- 2 seconds or more have passed since the staring sequence was completed.

Judgement Criteria
- Intake air temperature sensor output voltage has continued to be 0.2 volt or lower [corresponding to an air intake temperature of 115 °C (239 °F) or higher] for 2 seconds.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists

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

Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B

STEP 1.Using scan tool MB991958, check data list item 13: Intake Air Temperature Sensor.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.




1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to the data reading mode for item 13, Intake Air Temperature Sensor.
- The intake air temperature and temperature shown with the scan tool should approximately match.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the sensor operating properly?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.

NO: Go to Step 2.




STEP 2. Check harness connector B-105 at the intake air temperature sensor for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 3.

NO: Repair or replace it. Harness Connector Inspection. Then go to Step 6.

STEP 3. Check the intake air temperature sensor.




1. Disconnect the intake air temperature sensor connector B-105.




2. Measure the resistance between intake air temperature sensor side connector terminal No. 5 and No. 6.
- There should be continuity. (0.30 -1.0 kOhms)

Q: Is the measured resistance between 0.30 and 1.0 kOhms?

YES: Go to Step 4.

NO: Replace the volume airflow sensor. Then go to Step 6.







STEP 4. Check for short circuit to ground between intake air temperature sensor connector B-105 and ECM connector C-115.

Q: Is the harness wire in good condition?

YES: Go to Step 5.

NO: Repair it. Then go to Step 6.




STEP 5. Check harness connector C-115 at ECM for damage.

Q: Is the harness connector in good condition?

YES: Replace the ECM. Then go to Step 6.

NO: Repair or replace it. Harness Connector Inspection. Then go to Step 6.

STEP 6. Perform the OBD-II drive cycle.

1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0112 set?

YES: Repeat the troubleshooting.

NO: The procedure is complete.