SFI SYSTEM (w/ Dual VVT-i), Diagnostic DTC:P0037, P0038, P102D

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)
P102D O2 Sensor Heater Circuit Performance Bank 1 Sensor 2 Stuck ON

DESCRIPTION


Tech Tips


  • When any of these DTCs is stored, the ECM enters fail-safe mode. The ECM turns off the heated oxygen sensor heater in fail-safe mode. The ECM continues operating in fail-safe mode until the ignition switch is turned off.

  • The ECM provides a pulse-width modulated control circuit to adjust the current through the heater. The heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.

    A003GDDE01
DTC No. DTC Detection Condition Trouble Area
P0037

Heated oxygen sensor heater current less than 0.3 A.

(1 trip detection logic)

  • Open in heated oxygen sensor heater circuit

  • Heated oxygen sensor heater (Sensor 2)

  • No. 1 integration relay

  • ECM
P0038

Heated oxygen sensor heater current 2 A or more.

(1 trip detection logic)

  • Short in heated oxygen sensor heater circuit

  • Heated oxygen sensor heater (Sensor 2)

  • No. 1 integration relay

  • ECM
P102D

The heater current is higher than the specified value while the heater is not operating.

(1 trip detection logic)

 ECM

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.

Heated oxygen sensor heater range check (P0037, P0038 and P102D):

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.

Tech Tips

Normally, the heated oxygen sensor current is 0.4 to 1 A (when the engine is idling, the heated oxygen sensor is warmed up and battery voltage is 11 to 14 V).

CONFIRMATION DRIVING PATTERN

A003CFCE21

  1. Connect the GTS to the DLC3.

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

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

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

  5. Turn the ignition switch to ON and turn the GTS on [A].

  6. Start the engine and idle it for 5 minutes or more [B].

  7. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 3000 rpm for 1 minute [C].

  8. Idle the engine for 5 minutes or more [D].

  9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].

  10. Read the 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.

  11. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

  12. Input the DTC: P0037, P0038 or P102D.

  13. 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.

    • If the judgment result shows INCOMPLETE or N/A, perform steps [B] through [E] again.

WIRING DIAGRAM

A003HP5E01

INSPECTION PROCEDURE

Note

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

Tech Tips


  • Sensor 2 refers to the sensor mounted behind the Three-way Catalytic Converter (TWC) and located far 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.

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

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

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. CHECK TERMINAL VOLTAGE (+B OF HEATED OXYGEN SENSOR)

    A003EUVE52
    Text in Illustration
    *a

    Front view of wire harness connector

    (to Heated Oxygen Sensor)

    1. 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
      D35-2 (+B) - Body ground Ignition switch ON 11 to 14 V

    NG

    INSPECT NO. 1 INTEGRATION RELAY (EFI) 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
      Tester Connection Condition Specified Condition
      D35-1 (HT1B) - D116-55 (HT1B) Always Below 1 Ω
      D35-1 (HT1B) or D116-55 (HT1B) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK WHETHER DTC OUTPUT RECURS


    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. Start the engine and idle it for 5 minutes or more.

    7. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 3000 rpm for 1 minute.

    8. Idle the engine for 5 minutes or more.

    9. Read the output pending DTCs using the GTS.

      Result
      Result Proceed to
      No pending DTC is output A
      Pending DTC P0037, P0038 and/or P102D is output B

    B

    REPLACE ECM Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

  5. INSPECT NO. 1 INTEGRATION RELAY (EFI)


    1. Inspect the No. 1 integration relay (EFI) Click here.


    NG

    REPLACE NO. 1 INTEGRATION RELAY

    OK

  6. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - NO. 1 INTEGRATION RELAY)


    1. Disconnect the heated oxygen sensor connector.

    2. Remove the No. 1 integration relay from the No. 1 engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D35-2 (+B) - 10A-8 Always Below 1 Ω
      D35-2 (+B) or 10A-8 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    CHECK ECM POWER SOURCE CIRCUIT Click here