Dtc P0115 Engine Coolant Temperature Circuit Malfunction

Engine. Lexus Is250, Is220D. Gse20 Ale20
4Gr-Fse Engine Control System. Lexus Is250, Is220D. Gse20 Ale20

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE OF ENGINE COOLANT TEMPERATURE SENSOR (COOLANT TEMP)

CHECK ENGINE COOLANT TEMPERATURE SENSOR (CHECK FOR OPEN IN SENSOR)

CHECK ECM (CHECK FOR OPEN IN ECM)

CHECK ENGINE COOLANT TEMPERATURE SENSOR (CHECK FOR SHORT IN SENSOR)

CHECK ECM (CHECK FOR SHORT IN ECM)

DTC P0115 Engine Coolant Temperature Circuit Malfunction

DTC P0117 Engine Coolant Temperature Circuit Low Input

DTC P0118 Engine Coolant Temperature Circuit High Input


DESCRIPTION

A thermistor is built into the Engine Coolant Temperature (ECT) sensor, of which the resistance value varies according to the ECT.
The structure of the sensor and its connection to the ECM are the same as those of the Intake Air Temperature (IAT) sensor.
HINT:
When any of DTCs P0115, P0117 and P0118 are set, the ECM enters fail-safe mode. During fail-safe mode, the ECT is estimated to be 80°C (176°F) by the ECM. Fail-safe mode continues until a pass condition is detected.

DTC No.
Proceed to
DTC Detection Condition
Trouble Area
P0115
Step 1
Open or short in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Open or short in ECT sensor circuit
  1. ECT sensor
  1. ECM
P0117
Step 4
Short in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Short in ECT sensor
  1. ECT sensor
  1. ECM
P0118
Step 2
Open in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Open in ECT sensor circuit
  1. ECT sensor
  1. ECM
HINT:
When any of these DTCs are set, check the ECT by entering the following menus on the intelligent tester: Power train / Engine / Data List / Coolant Temp.

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

WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit Malfunction


INSPECTION PROCEDURE

HINT:
  1. 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.
  1. Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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 (Click here).
1.READ VALUE OF ENGINE COOLANT TEMPERATURE SENSOR (COOLANT TEMP)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    Between 80°C and 97°C (176°F and 207°F) with warm engine.

    Result:

    Temperature Displayed
    		Proceed to
    -40°C (-40°F)
    		A
    140°C (284°F) or higher
    		B
    Between 80°C and 97°C (176°F and 207°F)
    		C
    HINT:
    1. If there is an open circuit, the intelligent tester indicates -40°C (-40°F).
    2. If there is a short circuit, the intelligent tester indicates 140°C (284°F) or higher.


B
Go to step 4

C
CHECK FOR INTERMITTENT PROBLEMS
A


2.CHECK ENGINE COOLANT TEMPERATURE SENSOR (CHECK FOR OPEN IN SENSOR)


    Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit Malfunction

  1. Confirm good connection at the Engine Coolant Temperature (ECT) sensor.

  1. Disconnect the E40 ECT sensor connector.

  1. Connect terminals 1 and 2 of the ECT sensor connector on the wire harness side.

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    140°C (284°F) or higher.

  1. Reconnect the ECT sensor connector.



OK
REPLACE ENGINE COOLANT TEMPERATURE SENSOR
NG


3.CHECK ECM (CHECK FOR OPEN IN ECM)

  1. Confirm good connection at the ECM.



    Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit Malfunction

  1. Disconnect the E40 ECT sensor connector.

  1. Connect terminals THW and E2 of the E3 and E5 ECM connector.

    HINT:
    Before checking, do visual and contact pressure checks on the ECM connector.

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    140°C (284°F) or higher.

  1. Reconnect the ECT sensor connector.



OK
REPAIR OR REPLACE HARNESS OR CONNECTOR
NG

REPLACE ECM

4.CHECK ENGINE COOLANT TEMPERATURE SENSOR (CHECK FOR SHORT IN SENSOR)


    Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit Malfunction

  1. Disconnect the E40 ECT sensor connector.

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    -40°C (-40°F)

  1. Reconnect the ECT sensor connector.



OK
REPLACE ENGINE COOLANT TEMPERATURE SENSOR
NG


5.CHECK ECM (CHECK FOR SHORT IN ECM)


    Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit Malfunction

  1. Disconnect the E3 and E5 ECM connectors.

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    -40°C (-40°F)

  1. Reconnect the ECM connector.



OK
REPAIR OR REPLACE HARNESS OR CONNECTOR
NG

REPLACE ECM