SFI SYSTEM(w/ Canister Pump Module), 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

The air fuel ratio sensor (sensor 2) generates current that corresponds to the actual air fuel ratio. This sensor current is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection duration. If the air fuel ratio sensor (sensor 2) malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor (sensor 2) is a cup type sensor and uses a zirconia element for the sensor element. The zirconium element is made of platinum coated zirconium and includes an integrated heating element. The inner surface of the zirconia element is exposed to the outside air and the outer surface of it is exposed to the exhaust gas. The zirconia element generates a voltage according to the oxygen concentration of the exhaust gas and outside air. The air fuel ratio sensor (sensor 2) becomes very efficient when heated. When the exhaust gas temperature is low, the sensor does not generate useful voltage signals without supplementary heating. Therefore, the air fuel ratio sensor (sensor 2) includes a heater to heat the zirconia element.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel ratio.

B008GMNE04

Tech Tips


  • When any of these DTCs are stored, the ECM enters fail-safe mode. The ECM turns off the air fuel ratio sensor (sensor 2) heater in fail-safe mode. Fail-safe mode continues until the engine switch is turned off.

  • Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor (sensor 2).

  • The ECM has a pulse width modulated control circuit to adjust the current through the heater. The air fuel ratio sensor (sensor 2) heater circuit uses a relay on the +B side of the circuit.

    B008I1ZE12
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0037 Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2) Air fuel ratio sensor (sensor 2) heater current is the specified value or less while the heater is operating (1 trip detection logic).

  • Short in air fuel ratio sensor (sensor 2) heater circuit

  • Air fuel ratio sensor (sensor 2)

  • ECM

 Comes on DTC stored
P0038 Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 2) Air fuel ratio sensor (sensor 2) heater current is higher than the specified value while the heater is operating (1 trip detection logic).

  • Open or short in air fuel ratio sensor (sensor 2) heater circuit

  • Air fuel ratio sensor (sensor 2)

  • ECM

 Comes on DTC stored
P102D O2 Sensor Heater Circuit Performance Bank 1 Sensor 2 Stuck ON Air fuel ratio sensor (sensor 2) heater voltage is the specified value or less while the heater is not operating (1 trip detection logic).

  • Short in air fuel ratio sensor (sensor 2) heater circuit

  • Air fuel ratio sensor (sensor 2)

  • ECM

 Comes on DTC stored

MONITOR DESCRIPTION

The air fuel ratio sensor (sensor 2) detects oxygen levels in the exhaust gas and transmits the information to the ECM. The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of platinum-coated zirconia and includes an integrated heating element.

The zirconia element generates a small voltage when there is a large difference in the oxygen concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage generation.

The air fuel ratio sensor (sensor 2) is more efficient when heated. When the exhaust gas temperature is low, the sensor cannot generate useful current signals without supplementary heating. The ECM regulates the supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater element. If the heater current is outside the normal range, the signal transmitted by the air fuel ratio sensor (sensor 2) becomes inaccurate. As a result, the ECM is unable to regulate the air fuel ratio properly.



MONITOR STRATEGY

Frequency of Operation Continuous

TYPICAL ENABLING CONDITIONS

Time after heater on 5 seconds or more

CONFIRMATION DRIVING PATTERN

B008H5GE02

  1. Connect the GTS to the DLC3.

  2. Turn the engine switch on (IG) and turn the GTS on.

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

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

  5. Turn the engine switch on (IG) 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

B008H9RE04

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following 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" [A/F Heater Duty B1S2 and A/F Heater current Value B1S2].

    Click here

  • When the values for the Data List item A/F Heater current Value 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 for A/F Sensor function provided in the Active Test and monitor the air fuel ratio sensor (sensor 2) output current Click here. If the sensor output current does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

PROCEDURE


  1. INSPECT AIR FUEL RATIO SENSOR (SENSOR 2) (HEATER RESISTANCE)


    1. Inspect the air fuel ratio sensor (sensor 2).

      Click here

      Tech Tips

      Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 2).

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE AIR FUEL RATIO SENSOR (SENSOR 2) Click here

    OK

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR (SENSOR 2))


    1. B008J11C10
      *a

      Front view of wire harness connector

      (to Air Fuel Ratio Sensor (Sensor 2))

      Disconnect the air fuel ratio sensor (sensor 2) connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      I191-1 (+B) - Body ground Engine switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR (SENSOR 2) - EFI-MAIN NO.1 RELAY)

    OK

  3. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR (SENSOR 2) - ECM)


    1. Disconnect the air fuel ratio 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
      I191-2 (HA1B) - C65-56 (HA1B) Always Below 1 Ω
      I191-2 (HA1B) or C65-56 (HA1B) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.


      Powertrain > Engine and ECT > Trouble Codes

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

      Result
      Proceed to
      NEXT

    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC P0037, P0038 OR P102D)


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

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

    3. Read the pending DTCs.


      Powertrain > Engine and ECT > Trouble Codes
      Result
      Result Proceed to
      DTC is not output A
      DTC P0037, P0038 or P102D is output B

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

    B

    REPLACE ECM Click here