SFI SYSTEM (w/ Secondary Air Injection 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 Malfunction (Bank 1 Sensor 2)

DESCRIPTION

Refer to DTC P0136 Click here.

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.

    A01J74QE24
DTC No. DTC Detection Condition Trouble Area
P0037 The heater current is below the specified value while the heater is operating (1 trip detection logic).

  • Open in heated oxygen sensor heater circuit

  • Heated oxygen sensor heater (Sensor 2)

  • No. 1 integration relay

  • ECM
P0038 The heater current is higher than the specified value while the heater is operating (1 trip detection logic).

  • Short in heated oxygen sensor heater circuit

  • Heated oxygen sensor heater (Sensor 2)

  • No. 1 integration relay

  • ECM
P0141 The cumulative heater resistance correction value exceeds the threshold (2 trip detection logic).

  • Open or short in heated oxygen sensor heater circuit

  • Heated oxygen sensor heater (Sensor 2)

  • No. 1 integration relay

  • 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 and P0038):

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.

Heated oxygen sensor heater performance (P0141):

After the accumulated heater ON time exceeds 100 seconds, the ECM calculates the heater resistance using battery voltage and the current applied to the heater. If the resistance is above the threshold value, the ECM determines that there is a malfunction in the heated oxygen sensor heater and stores DTC P0141.

MONITOR STRATEGY

Frequency of Operation Continuous

TYPICAL ENABLING CONDITIONS

P0037 (Case 1)
Time after heater ON 10 seconds or more
P0037 (Case 2)
Time after heater ON 10 seconds or more
P0038
Time after heater ON 10 seconds or more
P0141
Time after fuel cut ON to OFF 30 seconds or more
Accumulated heater ON time 100 seconds or more
Duration that rear heated oxygen sensor impedance is less than 15 kΩ 2 seconds or more

CONFIRMATION DRIVING PATTERN

A01J681E21

  1. Connect the intelligent tester to the DLC3.

  2. Turn the ignition switch to ON and turn the intelligent tester 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 intelligent tester 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 / DTC [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 P0141.

  13. Check the DTC judgment result.

    Intelligent Tester 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

Refer to DTC P0136 Click here.

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 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.

  • 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)

    A01J4EFE53
    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
      H12-2 (+B) - Body ground Ignition switch ON 11 to 14 V

    NG

    INSPECT NO. 1 INTEGRATION RELAY (MAIN) 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
      H12-1 (HT1B) - E11-2 (HT1B) Always Below 1 Ω
      H12-1 (HT1B) or E11-2 (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 intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the intelligent tester on.

    4. Clear the DTCs Click here.

    5. Start the engine.

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

    7. Read the output pending DTCs using the intelligent tester.

      Result
      Result Proceed to
      No pending DTC is output A
      Pending DTC P0037, P0038 and/or P0141 is output B

    B

    REPLACE ECM Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

  5. INSPECT NO. 1 INTEGRATION RELAY (MAIN)


    1. Inspect the No. 1 integration relay (MAIN) 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 engine room relay block and junction block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H12-2 (+B) - 1J-5 Always Below 1 Ω
      H12-2 (+B) or 1J-5 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    CHECK ECM POWER SOURCE CIRCUIT Click here