SFI SYSTEM (w/o Secondary Air Injection System), Diagnostic DTC:P00B3, P00B4

DTC Code DTC Name
P00B3 Radiator Coolant Temperature Sensor Circuit Low
P00B4 Radiator Coolant Temperature Sensor Circuit High

DESCRIPTION

A thermistor, whose resistance value varies according to the engine coolant temperature (radiator), is built into the engine coolant temperature (radiator) sensor.

The structure of the sensor and its connection to the ECM are the same as those of the intake air temperature sensor.

Tech Tips

When DTC P00B3 or P00B4 is stored, the ECM enters fail-safe mode. During fail-safe mode, the engine coolant temperature (radiator) is estimated to be 80°C (176°F) by the ECM. The ECM continues operating in fail-safe mode until a pass condition is detected.

DTC No. DTC Detection Condition Trouble Area
P00B3 Short in the engine coolant temperature (radiator) sensor circuit for 0.5 seconds (1 trip detection logic).

  • Short in engine coolant temperature (radiator) sensor circuit

  • Engine coolant temperature (radiator) sensor

  • ECM
P00B4 Open in the engine coolant temperature (radiator) sensor circuit for 0.5 seconds (1 trip detection logic).

  • Open in engine coolant temperature (radiator) sensor circuit

  • Engine coolant temperature (radiator) sensor

  • ECM

Tech Tips

When any of these DTCs is stored, check the engine coolant temperature (radiator) by entering the following menus: Powertrain / Engine and ECT / Data List / Radiator Coolant Temp.

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

MONITOR DESCRIPTION

The engine coolant temperature (radiator) sensor is used to monitor the engine coolant temperature (radiator). The engine coolant temperature (radiator) sensor has a thermistor with a resistance that varies according to the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are reflected in the output voltage from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature (radiator). When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the engine coolant temperature (radiator) sensor and stores a DTC.

Example:

If the sensor output voltage is higher than 4.91 V for 0.5 seconds or more, the ECM determines that there is an open in the engine coolant temperature (radiator) sensor circuit and stores DTC P00B4. Conversely, if the voltage output is below 0.14 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit and stores DTC P00B3.

If the malfunction is not repaired successfully, a DTC is stored 0.5 seconds after the engine is next started.

WIRING DIAGRAM

A01BEF4E09

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records 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 INTELLIGENT TESTER (RADIATOR COOLANT TEMP)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the intelligent tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Radiator Coolant Temp.

    5. Read the value displayed on the intelligent tester.

      Standard value
      Between 75 and 100°C (167 and 212°F) with warm engine
      Result
      Result Proceed to
      -40°C (-40°F) A
      140°C (284°F) or higher B
      Between 75 and 100°C (167 and 212°F) C

      Tech Tips


      • If there is an open circuit, the intelligent tester indicates -40°C (-40°F).


      • If there is a short circuit, the intelligent tester indicates 140°C (284°F) or higher.


    B

    READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS) Click here

    C

    CHECK FOR INTERMITTENT PROBLEMS Click here

    A

  2. READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN WIRE HARNESS)

    A01BAYCE21
    Text in Illustration
    *1 engine coolant temperature (radiator) Sensor
    *2 ECM
    *a

    Front view of wire harness connector

    (to engine coolant temperature (radiator) Sensor)

    1. Disconnect the engine coolant temperature (radiator) sensor connector.

    2. Connect terminals 1 and 2 of the engine coolant temperature (radiator) sensor connector on the wire harness side.

    3. Connect the intelligent tester to the DLC3.

    4. Turn the ignition switch to ON.

    5. Turn the intelligent tester on.

    6. Enter the following menus: Powertrain / Engine and ECT / Data List / Radiator Coolant Temp.

    7. Read the value displayed on the intelligent tester.

      Standard value
      140°C (284°F) or higher

    NG

    CHECK HARNESS AND CONNECTOR (ENGINE COOLANT TEMPERATURE (RADIATOR) SENSOR - ECM) Click here

    OK

    CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE ENGINE COOLANT TEMPERATURE (RADIATOR) SENSOR

  3. CHECK HARNESS AND CONNECTOR (ENGINE COOLANT TEMPERATURE (RADIATOR) SENSOR - ECM)


    1. Disconnect the engine coolant temperature (radiator) sensor connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B29-2 - D97-66 (RTHW) Always Below 1 Ω
      B29-1 - D97-72 (E2) Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM Click here

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

    A01BHC2E34
    Text in Illustration
    *1 engine coolant temperature (radiator) Sensor
    *2 ECM

    1. Disconnect the engine coolant temperature (radiator) sensor connector.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the intelligent tester on.

    5. Enter the following menus: Powertrain / Engine and ECT / Data List / Radiator Coolant Temp.

    6. Read the value displayed on the intelligent tester.

      Standard value
      -40°C (-40°F)

    NG

    CHECK HARNESS AND CONNECTOR (ENGINE COOLANT TEMPERATURE (RADIATOR) SENSOR - ECM) Click here

    OK

    REPLACE ENGINE COOLANT TEMPERATURE (RADIATOR) SENSOR

  5. CHECK HARNESS AND CONNECTOR (ENGINE COOLANT TEMPERATURE (RADIATOR) SENSOR - ECM)


    1. Disconnect the engine coolant temperature (radiator) sensor connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B29-2 or D97-66 (RTHW) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here