P0111

DTC P0111: Intake Air Temperature Circuit Range/Performance Problem














CIRCUIT OPERATION

- Approximately 5 volts are applied to the intake air temperature sensor output terminal (terminal No. 1) from the ECM (terminal No. 89) via the resistor in the ECM. The ground terminal (terminal No. 4) is grounded with ECM (terminal No. 88).

- 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 does not change when specified go/stop operations are repeated.

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)

- Engine coolant temperature sensor

DTC SET CONDITIONS

Logic Flow Chart






Check Conditions

- Engine coolant temperature is higher than 76°C (169°F).

- Repeat 2 or more times: drive*1, stop*2.
- Drive*1: vehicle speed higher than 50 km/h (31 mph) lasting a total of more than 60 seconds.

- Stop*2: vehicle speed lower than 1.5 km/h (1.0 mph) lasting more than 30 seconds.
Judgement Criterion

- Changes in the intake air temperature is lower than 1°C (1.8°F).

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 8 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.

- ECM failed.

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)Remove the mass airflow sensor from the air intake hose.
(3)Turn the ignition switch to the "ON" position.
(4)Set scan tool MB991958 to the data reading mode for item 5, Intake Air Temperature Sensor.
(5)Heating the sensor using a hair drier.

- The indicated temperature increases.

NOTE:
Do not allow it to increase over 80°C (176°F).

(6)Turn the ignition switch to the "LOCK" (OFF) position.
(7)Attach the mass airflow sensor.

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 the intake air temperature sensor.

(1)Disconnect the intake air temperature sensor connector A-07.

(2)Remove the mass airflow sensor.





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





(4)Measure resistance while heating the sensor using a hair drier.
Standard value:

13 - 17 kohms [at -20°C (-4°F)]
5.3 - 6.7 kohms [at 0°C (32°F)]
2.3 - 3.0 kohms [at 20°C (68°F)]
1.0 - 1.5 kohms [at 40°C (104°F)]
0.56 - 0.76 kohms [at 60°C (140°F)]
0.30 - 0.45 kohms [at 80°C (176°F)]

Q. Is the measured resistance at the standard value?

YES Replace the mass airflow sensor. Then go to Step 3.

NO Go to Step 3.

STEP 3. 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 8 Monitors, Trips, Drive Cycles and Readiness Codes.

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

Q. Is DTC P0111 set?

YES Replace the ECM. When the ECM is replaced, register the ID code. Refer to ID registration procedure manual - ID codes registration judgement table [Vehicles with KOS] or ID registration procedure manual - ID codes registration judgement table [Vehicles with WCM].
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.