SFI SYSTEM, Diagnostic DTC:P003612, P003614, P102A9E

DTC Code DTC Name
P003612 HO2S Heater Control Circuit Bank 1 Sensor 2 Circuit Short to Battery
P003614 HO2S Heater Control Circuit Bank 1 Sensor 2 Circuit Short to Ground or Open
P102A9E O2 Sensor Heater Performance Bank 1 Sensor 2 Stuck On

DESCRIPTION

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 TWC (Three-Way Catalytic Converter) 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 level. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a heated oxygen sensor is used.

The heated oxygen sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).

When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is high. The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is lean (low voltage, i.e. less than 0.45 V).

Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas is low. The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is rich (high voltage, i.e. more than 0.45 V). The heated oxygen sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level.

The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air fuel ratio after the TWC is rich or lean, and adjusts the fuel injection duration accordingly. Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.

B0088B5E24

Tech Tips


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

  • The heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.

B0087TTE12
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory Note
P003612 HO2S Heater Control Circuit Bank 1 Sensor 2 Circuit Short to Battery Heated oxygen sensor heater current reaches high limit (1 trip detection logic).

  • Short in heated oxygen sensor heater circuit

  • Heated oxygen sensor

  • ECM

 Comes on DTC stored

SAE Code:

P0038
P003614 HO2S Heater Control Circuit Bank 1 Sensor 2 Circuit Short to Ground or Open Heated oxygen sensor heater current is the specified value or less while the heater is operating (1 trip detection logic).

  • Open or short in heated oxygen sensor heater circuit

  • Heated oxygen sensor

  • EFI-MAIN NO. 3 relay

  • ECM

 Comes on DTC stored

SAE Code:

P0037
P102A9E O2 Sensor Heater Performance Bank 1 Sensor 2 Stuck On Heated oxygen sensor heater current is higher than the specified value while the heater is not operating (1 trip detection logic).

  • Short in heated oxygen sensor heater circuit

  • ECM

 Comes on DTC stored

SAE Code:

P102D

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.


MONITOR STRATEGY

Frequency of Operation Continuous

TYPICAL ENABLING CONDITIONS

Time after heater on 10 seconds or more

CONFIRMATION DRIVING PATTERN

B0084W6E56

  1. Connect the GTS to the DLC3.

  2. Turn the engine switch on (IG).

  3. Turn the GTS on.

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

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

  6. Turn the engine switch on (IG) [A].

  7. Turn the GTS on.

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

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

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

  11. Enter the following menus: Powertrain / Engine / Trouble Codes [E].

  12. 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.

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

  14. Input the DTC: P003612, P003614 or P102A9E.

  15. 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

    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, perform steps [B] through [E] again.

WIRING DIAGRAM

B008696E03

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" [O2 Sensor Heater B1S2 and O2 Sensor Heater Current Value B1S2].

    Click here

  • When the values for the Data List item O2 Sensor Heater Current Value B1S2 is not 0 A, the heater is on.

  • Change the fuel injection volume using the Control the Injection Volume for A/F Sensor 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.

  • 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.

PROCEDURE


  1. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)


    1. Inspect the heated oxygen sensor.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE HEATED OXYGEN SENSOR Click here

    OK

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

    B0088VZC03
    *a

    Front view of wire harness connector

    (to Heated Oxygen Sensor)

    1. Disconnect the heated oxygen sensor 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
      C95-2 (+B) - Body ground Engine switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT EFI-MAIN NO. 3 RELAY 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
      C95-1 (HT1B) - C58-17 (HT1B) Always Below 1 Ω
      C95-1 (HT1B) or C58-17 (HT1B) - Body ground and other terminals 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 > Clear DTCs

    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 P003612, P003614 OR P102A9E)


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

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

    3. Read the DTCs.


      Powertrain > Engine > Trouble Codes
      Result
      Result Proceed to
      DTCs are not output A
      DTC P003612, P003614 or P102A9E is output B

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

    B

    REPLACE ECM Click here

  6. INSPECT EFI-MAIN NO. 3 RELAY


    1. Inspect the EFI-MAIN NO. 3 relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE EFI-MAIN NO. 3 RELAY

    OK

  7. CHECK TERMINAL VOLTAGE (POWER SOURCE OF EFI-MAIN NO. 3 RELAY)

    B0083YAC01
    *1 Engine Room Relay Block and Junction Block Assembly
    *2 EFI-MAIN NO. 3 Relay

    1. Remove the EFI-MAIN NO. 3 relay from the engine room relay block and junction block assembly.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      3 (EFI-MAIN NO. 3 relay) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - EFI-MAIN NO. 3 RELAY)

    OK

  8. CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 3 RELAY - BODY GROUND)


    1. Remove the EFI-MAIN NO. 3 relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 (EFI-MAIN NO. 3 relay) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  9. CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 3 RELAY - HEATED OXYGEN SENSOR)


    1. Remove the EFI-MAIN NO. 3 relay from the engine room relay block and junction block assembly.

    2. Disconnect the heated oxygen sensor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      5 (EFI-MAIN NO. 3 relay) - C95-2 (+B) Always Below 1 Ω
      5 (EFI-MAIN NO. 3 relay) or C95-2 (+B) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI-MAIN NO. 1 RELAY - EFI-MAIN NO. 3 RELAY)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR