P0112

DTC P0112: Intake Air Temperature Circuit Low Input

CAUTION:
If DTC P0112 has been set, TCL related DTC U1120 is also set. After P0112 has been diagnosed, don't forget to erase DTC U1120.














CIRCUIT OPERATION

- Approximately 5 volts are applied to the intake air temperature sensor output terminal (terminal No. 1) from the ECM [M/T] or the PCM [A/T] (terminal No. 107) via the resistor in the ECM [M/T] or the PCM [A/T]. The ground terminal (terminal No. 4) is grounded with ECM [M/T] or PCM [A/T] (terminal No. 69).
- 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 [M/T] or the PCM [A/T] 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 below)

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

- Not applicable

DTC SET CONDITIONS

Logic Flow Chart






Check Condition

- 2 seconds or more have passed since the engine starting sequence was completed.
Judgement Criterion

- 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 - Pattern 23 Monitors, Trips, Drive Cycles and Readiness Codes .

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.[ M/T]
- PCM failed.[ A/T]

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

STEP 1. Using scan tool MB991958, check data list item 5: 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 5, 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. How to Cope With Intermittent Malfunctions.

NO Go to Step 2.

STEP 2. Check harness connector B-09 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-09.





(2)Measure the resistance between intake air temperature sensor side connector terminal No. 1 and No. 4.

- There should be continuity. (0.30 - 20 kohms)

Q. Is the measured resistance between 0.30 and 20 kohms?

YES Go to Step 4.

NO Replace the mass airflow sensor. Then go to Step 6.

STEP 4. Check for short circuit to ground between intake air temperature sensor connector B-09 (terminal No. 1) and ECM [M/T] or PCM [A/T] connector B-21 (terminal No. 107).









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 B-21 at ECM [M/T] or PCM [A/T] for damage.





Q. Is the harness connector in good condition?

YES Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Immobilizer System.
Then go to Step 6.

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

STEP 6. 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 23 Monitors, Trips, Drive Cycles and Readiness Codes.

(2)Check the diagnostic trouble code (DTC).

Q. Is DTC P0112 set?

YES Retry the troubleshooting.
NO The inspection is complete.