P0110

1NZ-FE 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 selecting the following menu items on a Techstream: 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 sets a DTC.
Example:
If the sensor output voltage is more than 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 less 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: Read freeze frame data using a Techstream. Freeze frame data record 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 VALUE USING TECHSTREAM (INTAKE AIR TEMPERATURE)
(a) Connect a Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the tester ON.
(d) Select the following menu items: Powertrain / Engine and ECT / 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, the tester indicates -40°C (-40°F).
- If there is a short circuit, the tester indicates 140°C (284°F) or higher.

C -- CHECK FOR INTERMITTENT PROBLEMS
B -- READ VALUE USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS)
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (CHECK FOR OPEN IN WIRE HARNESS)




(a) Disconnect the C26 Mass Air Flow (MAF) meter connector.
(b) Connect terminals THA and E2 of the MAF meter wire harness side connector.
(c) Connect the Techstream to the DLC3.
(d) Turn the ignition switch to ON.
(e) Turn the tester ON.
(f) Select the following menu items: Powertrain / Engine and ECT / All Data / Intake Air.
(g) Read the value displayed on the tester.
Standard:
140°C (284°F) or higher
(h) Reconnect the MAF meter connector.
OK -- CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE MASS AIR FLOW METER
NG -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)




(a) Disconnect the C26 MAF meter connector.
(b) Disconnect the C20 ECM connector.
(c) Check the resistance.
Standard resistance:





(d) Reconnect the MAF meter connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM
4. READ VALUE USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS)




(a) Disconnect the C26 MAF meter connector.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to ON.
(d) Turn the tester ON.
(e) Select the following menu items: Powertrain / Engine and ECT / 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 HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)




(a) Disconnect the C26 MAF meter connector.
(b) Disconnect the C20 ECM connector.
(c) Check the resistance.
Standard resistance:





(d) Reconnect the MAF meter connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM