P0112

2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0110,P0112,P0113: Intake Air Temperature Circuit

DESCRIPTION

The intake air temperature sensor, mounted on the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature 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 intake air temperature sensor is powered by a 5 V applied from the THA terminal of the ECM, via resistor R.

Resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, according to changes in the intake air temperature, 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 intake air temperature 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: 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. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the intake air temperature sensor and sets a DTC.

Example:

- If the sensor voltage output is -40°C (-40°F) for 0.5 seconds or more, the ECM determines that there is an open in the intake air temperature sensor circuit, and sets DTC P0113. Conversely, if the voltage output is more than 140°C (284°F) 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 E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
- Read freeze frame data using the 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.

PROCEDURE

1. READ VALUE USING TECHSTREAM (INTAKE AIR TEMPERATURE)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch on (IG).

(c) Turn the tester on.

(d) Select the following menu items: Powertrain / Engine and ECT / Data List / Intake Air.

(e) Read the value displayed on the tester.

Standard:

Same as actual intake air temperature.

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 -- 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 mass air flow meter connector.

(b) Connect terminals THA and E2 of the mass air flow meter wire harness side connector.

(c) Connect the Techstream to the DLC3.

(d) Turn the ignition switch on (IG).

(e) Turn the tester on.

(f) Select the following menu items: Powertrain / Engine and ECT / Data List / Intake Air.

(g) Read the value displayed on the tester.

Standard:

140°C (284°F) or higher

Text in Illustration

(h) Reconnect the mass air flow meter connector.

NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

OK -- REPLACE MASS AIR FLOW METER Components

3. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

(a) Disconnect the mass air flow meter connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:

Check for open
Check for short

(d) Reconnect the mass air flow meter connector.

(e) Reconnect the ECM connector.

NG -- REPLACE ECM Components

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER - ECM)

4. READ VALUE USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS)

(a) Disconnect the mass air flow meter connector.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch on (IG).

(d) Turn the tester on.

(e) Select the following menu items: Powertrain / Engine and ECT / Data List / Intake Air.

(f) Read the value displayed on the tester.

Standard:

-40°C (-40°F)

Text in Illustration

(g) Reconnect the mass air flow meter connector.

NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

OK -- REPLACE MASS AIR FLOW METER

5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

(a) Disconnect the mass air flow meter connector.

(g) Reconnect the mass air flow meter connector.

NG -- REPLACE ECM Components

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER - ECM)