SFI SYSTEM, Diagnostic DTC:P0138

DTC Code DTC Name
P0138 Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)

DESCRIPTION

Refer to DTC P0137.

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DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0138

Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)

  • All of the following conditions are met (3 trip detection logic):

    1. Target lambda*1 is more than 0.995.

    2. Heated oxygen sensor (sensor 2) output voltage is more than 3.5 V.

    3. Conditions (a) and (b) are met continuously for 0.5 seconds.

    4. 100 seconds have elapsed since condition (c) was met and heated oxygen sensor (sensor 2) dew point judgment*2 was completed.

  • Short in signal output circuit and power source circuit of heated oxygen sensor (sensor 2)

  • Heated oxygen sensor (sensor 2)

  • ECM

Comes on

DTC stored
Tip:

  • *1: Target lambda value of the ECM.

    • Target lambda value is 1.0: stoichiometric air-fuel ratio

    • Target lambda value is more than 1.0: lean control performed

    • Target lambda value is less than 1.0: rich control performed

  • *2: Condensation may form in the exhaust pipes after the engine is started and before the exhaust system has warmed up. If condensation exists, the sensor element may be damaged if the heated oxygen sensor (sensor 2) heater is heated excessively. Therefore, the ECM will restrict the output of the heated oxygen sensor (sensor 2) heater until it determines condensation is not forming in the exhaust pipes. Dew point judgment is when the ECM judges that condensation is no longer forming.

  • The normal output voltage from the heated oxygen sensor (sensor 2) is 0 to 1.0 V.

WIRING DIAGRAM

Refer to DTC P0130.

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CONFIRMATION DRIVING PATTERN

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

DTC P0138 is detected when the vehicle is driven at an average vehicle speed of approximately 50 km/h (31 mph) in the city for approximately 30 minutes.

CAUTION / NOTICE / HINT

Note:

After replacing the ECM, perform idle learning.

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Tip:

  • Inspect the heated oxygen sensor (sensor 2) output voltage:

    Read the heated oxygen sensor (sensor 2) output voltage using the GTS.

    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Turn the GTS on.

    4. Allow the engine to idle for 20 minutes or more.

    5. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / O2S B1S2.

    6. Read the output voltage of the heated oxygen sensor (sensor 2).

      Standard voltage

      Heated oxygen sensor (sensor 2) output is below 1.0 V.

  • Sensor 1 refers to the sensor closest to the engine assembly.

  • Sensor 2 refers to the sensor farthest away from the engine assembly.

  • Read freeze frame data using the GTS. 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. INSPECT HEATED OXYGEN SENSOR (SENSOR 2)

    A213354C03

    *a

    Component without harness connected

    (Heated Oxygen Sensor (Sensor 2))

    1. Disconnect the heated oxygen sensor (sensor 2) connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      1 (+B) - 4 (OX1B)

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE HEATED OXYGEN SENSOR (SENSOR 2)

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    OK

  2. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR (SENSOR 2) - ECM)

    1. Disconnect the heated oxygen sensor (sensor 2) 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

      B31-103 (OX1B) - B31-25 (HT1B)

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE ECM

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    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR