LEMON Manuals: Even more car manuals for everyone
Home >> Lexus >> 2008 >> IS F >> Repair and Diagnosis (Single Page) >> Engine Performance >> Testing & Diagnosis >> Engine Control System - SFI System Diagnostics (1 Of 4) >> DTC P0112 Intake Air Temperature Circuit Low Input; DTC P0113 Intake Air Temperature Circuit High Input >> Description

DTC P0112 Intake Air Temperature Circuit Low Input; DTC P0113 Intake Air Temperature Circuit High Input: Description

Fig 1: Temperature Versus Resistance Graph
G05751472Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The intake air temperature sensor, in 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 supply 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 drivability

HINT:

When any of DTCs 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

DTC DETECTION CONDITION CHART

DTC No. DTC Detection Condition Trouble Area
P0112 Short in intake air temperature sensor circuit for 0 5 seconds
(1 trip detection logic)
  • Short in intake air temperature sensor circuit
  • Intake air temperature sensor (built into mass air flow meter)
  • ECM
P0113 Open in intake air temperature sensor circuit for 0 5 seconds
(1 trip detection logic)
  • Open in intake air temperature sensor circuit
  • Intake air temperature sensor (built into mass air flow meter)
  • ECM

HINT

When any of these DTCs are set, check the intake air temperature by entering the following menus Powertrain / Engine / Data List / Intake Air.

TEMPERATURE DISPLAYED MALFUNCTION CHART

Temperature Displayed Malfunction
-40°C (-40°F) Open circuit
140°C (284°F) or higher Short circuit