SFI SYSTEM, Diagnostic DTC:P0137

DTC Code DTC Name
P0137 Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)

DESCRIPTION

In order to obtain a high purification rate for the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a Three-Way Catalytic Converter (TWC) is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel ratio. The No. 2 heated oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoichiometric air fuel ratio. This is used to detect the oxygen concentration in the exhaust gas and provide the ECM with feedback to control the air fuel ratio. When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas increases. The No. 2 heated oxygen sensor informs the ECM of the lean condition (low voltage, i.e. less than 0.45 V). When the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas is reduced, and the No. 2 heated oxygen sensor informs the ECM of the rich condition (high voltage, i.e. higher than 0.45 V).

The ECM judges, using the voltage output of the No. 2 heated oxygen sensor, whether the air fuel ratio is rich or lean and controls the injection time accordingly. If a malfunction of the No. 2 heated oxygen sensor causes an output of abnormal voltage, the ECM is unable to perform accurate air fuel ratio control. The No. 2 heated oxygen sensor includes a heater which heats the zirconia element. The heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), a current flows to the heater in order to heat the sensor for accurate oxygen concentration detection.

A01VL2ZE01
DTC No. DTC Detection Condition Trouble Area
P0137

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


  • (1). Fuel-cut operation is not being performed.

  • (2). Purge control* of the catalyst is not being performed.

  • (3). No. 2 heated oxygen sensor output voltage is less than 0.06 V.

  • (4). Conditions (1), (2) and (3) are met for 5 seconds or more.

  • (5). Active air fuel ratio control is performed as follows after condition (4) is met:


    • (a) Pulse signal is applied to No. 2 heated oxygen sensor signal line.

    • (b) Difference in No. 2 heated oxygen sensor voltage before and after applying pulse signal is calculated.

    • (c) Steps (a) and (b) are repeated 3 more times.

  • (6). Average difference in No. 2 heated oxygen sensor voltage when active air fuel ratio control is performed 3 times is less than 0.015 V.

  • No. 2 heated oxygen sensor circuit

  • No. 2 heated oxygen sensor

  • ECM

Tech Tips

*: In order to purge oxygen adsorbed to the TWC, the stoichiometric ratio is controlled to rich side.

WIRING DIAGRAM

Refer to DTC P0130 Click here.

CAUTION / NOTICE / HINT

Note


  • Perform idle learning after replacing the ECM Click here.

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tech Tips


  • 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. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0137)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    5. Read pending DTCs.

      Result
      Result Proceed to
      DTC P0137 is output A
      DTC P0137 and other DTCs are output B

      Tech Tips

      If may DTCs other than P0137 are output, troubleshoot shoes DTCs first.


    B

    GO TO DTC CHART Click here

    A

  2. INSPECT NO. 2 HEATED OXYGEN SENSOR


    1. Inspect the No. 2 heated oxygen sensor Click here.


    NG

    REPLACE NO. 2 HEATED OXYGEN SENSOR Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (NO. 2 HEATED OXYGEN SENSOR - ECM)


    1. Disconnect the B83 No. 2 heated oxygen sensor connector.

    2. Disconnect the B97 ECM connector (for LHD).

    3. Disconnect the B101 ECM connector (for RHD).

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

      Standard Resistance
      for LHD
      Tester Connection Condition Specified Condition
      B83-4 (OX1B) - B97-103 (OX1B) Always Below 1 Ω
      B83-2 (HT1B) - B97-25 (HT1B) Always Below 1 Ω
      B83-3 (E1) - B97-135 (E12) Always Below 1 Ω
      B83-4 (OX1B) or B97-103 (OX1B) - Body ground Always 10 kΩ or higher
      B83-2 (HT1B) or B97-25 (HT1B) - Body ground Always 10 kΩ or higher
      for RHD
      Tester Connection Condition Specified Condition
      B83-4 (OX1B) - B101-103 (OX1B) Always Below 1 Ω
      B83-2 (HT1B) - B101-25 (HT1B) Always Below 1 Ω
      B83-3 (E1) - B101-135 (E12) Always Below 1 Ω
      B83-4 (OX1B) or B101-103 (OX1B) - Body ground Always 10 kΩ or higher
      B83-2 (HT1B) or B101-25 (HT1B) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPLACE NO. 2 HEATED OXYGEN SENSOR


    1. Replace the NO. 2 heated oxygen sensor Click here.


    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC P0137)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs Click here.

    5. Turn the ignition switch off and wait for at least 30 seconds.

    6. Turn the ignition switch to ON.

    7. Turn the GTS on.

    8. Start the engine and warm it up.

    9. Read the pending DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P0137 is output B

    OK

    END

    NG

    REPLACE ECM Click here