P0112
3UR-FE ENGINE CONTROL: SFI SYSTEM: P0110: Intake Air Temperature Circuit Malfunction
DTC P0110 - Intake Air Temperature Circuit Malfunction
DTC P0112 - Intake Air Temperature Circuit Low Input
DTC P0113 - Intake Air Temperature Circuit High Input
DESCRIPTION
- The Intake Air Temperature (IAT) sensor, mounted on the Mass Air Flow (MAF) meter, monitors the IAT. The IAT sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the IAT is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (See Fig. 1).
- The IAT sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
- Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor changes, according to changes in the IAT, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.
HINT: When any of DTCs P0110, P0112 and P0113 is stored, the ECM enters fail-safe mode. During fail-safe mode, the IAT is estimated to be 20°C (68°F) by the ECM. Fail-safe mode continues until a pass condition is detected.
HINT: When any of these DTCs are output, check the IAT by entering the following menus: Powertrain / Engine and ECT / All Data / Intake Air.
MONITOR DESCRIPTION
The ECM monitors the sensor voltage and uses this value to calculate the IAT. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the IAT sensor and stores a DTC.
Example:
If the sensor output voltage is higher than 4.91 V for 0.5 seconds or more, the ECM determines that there is an open in the IAT sensor circuit, and stores DTC P0113. Conversely, if the output voltage is below 0.18 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and stores DTC P0112.
If the malfunction is not repaired successfully, a DTC is stored 0.5 seconds after the engine is next started.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
P0110:
P0112:
P0113:
COMPONENT OPERATING RANGE
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT: Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
1. READ OUTPUT DTC
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(d) Read DTCs.
Result
C -- READ VALUE USING TECHSTREAM (CHECK FOR OPEN IN WIRE HARNESS)
B -- PERFORM ACTIVE TEST USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS) Data List / Active Test
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (INTAKE AIR TEMPERATURE)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / All Data / Intake Air.
(e) Read the value displayed on the Techstream.
Standard:
Same as actual Intake Air Temperature (IAT).
Result
HINT:
- If there is an open circuit, the Techstream indicates -40°C (-40°F).
- If there is a short circuit, the Techstream indicates 140°C (284°F) or higher.
C -- CHECK FOR INTERMITTENT PROBLEMS Check For Intermittent Problems
B -- PERFORM ACTIVE TEST USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS) Data List / Active Test
A -- Continue to next step.
3. READ VALUE USING TECHSTREAM (CHECK FOR OPEN IN WIRE HARNESS)
(a) Disconnect the C3 Mass Air Flow (MAF) meter connector.
(b) Connect terminals 4 (THA) and 5 (E2) of the MAF meter wire harness side connector.
(c) Connect the Techstream to the DLC3.
(d) Turn the engine switch on (IG).
(e) Turn the Techstream on.
(f) Enter the following menus: Powertrain / Engine and ECT / All Data / Intake Air.
(g) Read the value displayed on the Techstream.
Standard value:
140°C (284°F) or higher
NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
OK -- CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE MASS AIR FLOW METER
4. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the C3 MAF meter connector.
(b) Disconnect the C53 ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM
5. PERFORM ACTIVE TEST USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS) Data List / Active Test
(a) Disconnect the C3 MAF meter connector.
(b) Connect the Techstream to the DLC3.
(c) Turn the engine switch on (IG).
(d) Turn the Techstream on.
(e) Enter the following menus: Powertrain / Engine and ECT / All Data / Intake Air.
(f) Read the value displayed on the Techstream.
Standard value:
-40°C (-40°F)
NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
OK -- REPLACE MASS AIR FLOW METER
6. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the C3 MAF meter connector.
(b) Disconnect the C53 ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM