P0112

4GR-FSE ENGINE CONTROL SYSTEM: 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 are set, 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 set, check the IAT by entering the following menus on Techstream: Powertrain / Engine and ECT / Data List / All Data / Intake Air.





MONITOR DESCRIPTION

The ECM monitors the sensor voltage and uses this value to calculate the Intake Air Temperature (IAT). When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the IAT sensor and sets a DTC.
- Example:
If the sensor output voltage is 4.91 V for 0.5 seconds or more, the ECM determines that there is an open in the IAT sensor circuit, and sets DTC P0113. Conversely, if the output voltage is more than 0.18 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and sets DTC P0112.
If the malfunction is not repaired successfully, a DTC is set 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:
- If other DTCs relating to different systems that have terminal E3 as the ground terminal are output simultaneously, terminal E3 may have an open circuit.
- Read freeze frame data using Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction Freeze Frame Data.

PROCEDURE

1. READ VALUE USING INTAKE AIR TEMPERATURE SENSOR (INTAKE AIR)
(a) Connect Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the tester on.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
(e) Read the value displayed on the tester.
Standard:
Same as actual Intake Air Temperature (IAT).
Result:





HINT:
- If there is an open circuit, Techstream indicates -40°C (-40°F).
- If there is a short circuit, Techstream indicates 140°C (284°F).

C -- CHECK FOR INTERMITTENT PROBLEMS
B -- CHECK INTAKE AIR TEMPERATURE SENSOR (CHECK FOR SHORT IN SENSOR)
A -- Continue to next step.
2. CHECK INTAKE AIR TEMPERATURE SENSOR (CHECK FOR OPEN IN SENSOR)




(a) Confirm good connection of the mass air flow meter.
(b) Disconnect the E29 Mass Air Flow (MAF) meter connector.
(c) Connect terminals THA and E3 of the MAF meter wire harness side connector.
(d) Connect Techstream to the DLC3.
(e) Turn the engine switch on (IG).
(f) Turn the tester on.
(g) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
(h) Read the value displayed on the tester.
Standard:
140°C (284°F)
(i) Reconnect the MAF meter connector.
OK -- REPLACE MASS AIR FLOW METER
NG -- Continue to next step.
3. CHECK ECM (CHECK FOR OPEN IN ECM)




(a) Confirm good connection of the ECM.
(b) Disconnect the E29 MAF meter connector.
(c) Connect terminals THA and E3 of the E5 ECM connector.
HINT:
Before checking, do visual and contact pressure checks on the ECM connector.
(d) Connect Techstream to the DLC3.
(e) Turn the engine switch on (IG).
(f) Turn the tester on.
(g) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
(h) Read the value displayed on the tester.
Standard:
140°C (284°F)
(i) Reconnect the MAF meter connector.
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR
NG -- REPLACE ECM
4. CHECK INTAKE AIR TEMPERATURE SENSOR (CHECK FOR SHORT IN SENSOR)




(a) Disconnect the E29 MAF meter connector.
(b) Connect Techstream to the DLC3.
(c) Turn the engine switch on (IG).
(d) Turn the tester on.
(e) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
(f) Read the value displayed on the tester.
Standard:
-40°C (-40°F)
(g) Reconnect the MAF meter connector.
OK -- REPLACE MASS AIR FLOW METER
NG -- Continue to next step.
5. CHECK ECM (CHECK FOR SHORT IN ECM)




(a) Disconnect the E5 ECM connector.
(b) Connect Techstream to the DLC3.
(c) Turn the engine switch on (IG).
(d) Turn the tester on.
(e) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.
(f) Read the value displayed on the tester.
Standard:
-40°C (-40°F)
(g) Reconnect the ECM connector.
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR
NG -- REPLACE ECM