SFI SYSTEM, Diagnostic DTC:P0037, P0038, P0141

DTC Code DTC Name
P0037 Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
P0038 Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 2)
P0141 Oxygen Sensor Heater Circuit (Bank 1 Sensor 2)

DESCRIPTION

Refer to DTC P0137 Click here.

DTC No. DTC Detection Condition Trouble Area
P0037

Heated oxygen sensor heater voltage is less than battery voltage X 0.3 V for 10 seconds or more.

(2 trip detection logic)

  • Open or short in heated oxygen sensor heater circuit

  • Heated oxygen sensor

  • ECM
P0038

Heated oxygen sensor heater voltage is battery voltage X 0.2 V or more for 10 seconds or more.

(2 trip detection logic)
P0141

Heated oxygen sensor heater voltage is less than battery voltage X 0.88 V for 10 seconds or more.

(2 trip detection logic)

MONITOR DESCRIPTION

The sensing portion of the heated oxygen sensor has a zirconia element which is used to detect the oxygen concentration in the exhaust gas. If the zirconia element is at the appropriate temperature, and the difference between the oxygen concentrations surrounding the inside and outside surfaces of the sensor is large, the zirconia element generates voltage signals. In order to increase the oxygen concentration detecting capacity of the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor.

The ECM monitors the current applied to the heated oxygen sensor heater to check the heater for malfunctions.

If the heater current is outside the normal range, the signal transmitted by the heated oxygen sensor becomes inaccurate. When the current in the heated oxygen sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and stores a DTC.

CONFIRMATION DRIVING PATTERN


  1. A004ISCE17

  2. Connect the GTS to the DLC3.

  3. Turn the ignition switch to ON and turn the GTS on.

  4. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation) Click here.

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

  6. Turn the ignition switch to ON and turn the GTS on.

  7. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

  8. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of between 2500 and 3000 rpm for 40 seconds or more [A].

  9. Drive the vehicle at 10 km/h (6.25 mph) or more for 1 minute or more [B].

    CAUTION:

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

  10. Enter the following menus: Powertrain / Engine / Trouble Codes.

  11. Read pending DTCs.

    Tech Tips


    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

  12. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

  13. Input the DTC: P0037, P0038 or P0141.

  14. Check the DTC judgment result.

    GTS Display Description
    NORMAL

    • DTC judgment completed

    • System normal
    ABNORMAL

    • DTC judgment completed

    • System abnormal
    INCOMPLETE

    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions
    N/A

    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    Tech Tips


    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

  15. If the test result is INCOMPLETE or N/A and no DTC is output, perform a universal trip and check for permanent DTCs Click here.

    Tech Tips


    • If a permanent DTC is output, the system is malfunctioning.

    • If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

A004I4BE04

CAUTION / NOTICE / HINT

Note

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.

  • Refer to "Data List / Active Test" [O2 Heater B1S2 and O2 Heater Curr Val B1S2] Click here.

  • When the values for the Data List item O2 Heater Curr Val B1S2 is not 0 A, the heater is on.

  • Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.

  • Change the fuel injection volume using the Control the Injection Volume function provided in the Active Test and monitor the heated oxygen sensor output voltage Click here. If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

PROCEDURE


  1. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)


    1. Inspect the heated oxygen sensor Click here.


    NG

    REPLACE HEATED OXYGEN SENSOR Click here

    OK

  2. INSPECT TERMINAL VOLTAGE (POWER SOURCE OF HEATED OXYGEN SENSOR)


    1. A004KS0E03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Heated Oxygen Sensor)

      Disconnect the heated oxygen sensor connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      C13-2 (+B) - Body ground Ignition switch ON 11 to 14 V

    NG

    INSPECT RELAY (EFI MAIN2) Click here

    OK

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


    1. Disconnect the heated oxygen sensor connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance (Check for open)
      Tester Connection Condition Specified Condition
      A36-6 (HT1B) - C13-1 (HT1B) Always Below 1 Ω
      Standard Resistance (Check for short)
      Tester Connection Condition Specified Condition
      A36-6 (HT1B) or C13-1 (HT1B)- Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK WHETHER DTC OUTPUT RECURS (DTC P0037, P0038 OR P0141)


    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.

    9. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

    10. Enter the following menus: Powertrain / Engine / Trouble Codes.

    11. Read pending DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P0037, P0038 or P0141 is output B

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

    B

    REPLACE ECM Click here

  5. INSPECT RELAY (EFI MAIN2)


    1. Check the EFI MAIN2 relay Click here.


    NG

    REPLACE RELAY (EFI MAIN2)

    OK

  6. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - EFI MAIN2 RELAY)


    1. Disconnect the heated oxygen sensor connector.

    2. Remove the EFI MAIN2 relay from the engine room relay block assembly.

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

      Standard Resistance (Check for open)
      Tester Connection Condition Specified Condition
      EFI MAIN2 relay terminal 3 - C13-2 (+B) Always Below 1 Ω
      Standard Resistance (Check for short)
      Tester Connection Condition Specified Condition
      EFI MAIN2 relay terminal 3 or C13-2 (+B) - Body ground Always 10 kΩ or higher

    OK

    CHECK ECM POWER SOURCE CIRCUIT Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR