SFI SYSTEM, Diagnostic DTC:P0136, P0156

DTC Code DTC Name
P0136 Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)
P0156 Oxygen Sensor Circuit Malfunction (Bank 2 Sensor 2)

DESCRIPTION

The heated oxygen sensor is used to monitor oxygen concentration in the exhaust gas. For optimum catalytic converter operation, the air-fuel mixture must be maintained near the ideal stoichiometric air-fuel ratio. The heated oxygen sensor output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. The ECM adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The heated oxygen sensor generates a voltage between 0.1 and 0.9 V in response to oxygen concentration in the exhaust gas.

If the oxygen concentration in the exhaust gas increases, the air-fuel ratio is called LEAN. The heated oxygen sensor voltage drops below 0.45 V, which informs the ECM of the LEAN condition.

If oxygen is not in the exhaust gas, the air-fuel ratio is called RICH. The heated oxygen sensor voltage increases above 0.45 V, which informs the ECM of the RICH condition.

A001BOQE01
DTC No. DTC Detection Condition Trouble Area

P0136

P0156

Either of following conditions (a) or (b) is met :

(a) HO2 sensor voltage remains below 0.4 V (lean) or above 0.5 V (rich) while vehicle is repeatedly accelerated and decelerated for 4 minutes or more

(b) HO2 sensor voltage remains below 0.05 V for a long time period

  • Open or short in heated oxygen sensor (sensor 2) circuit

  • Heated oxygen sensor (sensor 2)

  • Heated oxygen sensor (sensor 2) heater

  • EFI relay (EFI MAIN2)

MONITOR DESCRIPTION

The ECM monitors the heated oxygen sensor (sensor 2) to make sure:


WIRING DIAGRAM

A001F8PE03

Refer to ECM Power Source Circuit Click here.

CONFIRMATION DRIVING PATTERN

A001FPOE44






Tech Tips

If a malfunction exists, the MIL will be illuminated on the multi-information display.

Note

If the conditions in this test are not strictly followed, detection of a malfunction will not occur. If you do not have the intelligent tester, turn the engine switch off after performing steps "c" to "f", and then perform steps "c" to "f" again.

CAUTION / NOTICE / HINT

Tech Tips

It is possible that the malfunctioning area can be found using the Active Test Control operation. The Active Test can determine if the heated oxygen sensor or other potential trouble areas are malfunctioning or not.

The injection volume can be switched to -12.5% (decrease) or +24.8% (increase) by the Active Test.

The Active Test procedure enables a technician to check and graph the output voltage of the heated oxygen sensors.


Tech Tips


  • The Control the Injection Volume operation lowers the fuel injection volume by 12.5% or increases the injection volume by 24.8%.

  • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Tester Display Injection Volume Status Voltage
O2S B1S1 or O2S B2S1 +24.8% Rich More than 0.55 V
O2S B1S1 or O2S B2S1 -12.5% Lean Less than 0.4 V
O2S B1S2 or O2S B2S2 +24.8% Rich More than 0.5 V
O2S B1S2 or O2S B2S2 -12.5% Lean Less than 0.4 V

Note

The heated oxygen sensor (sensor 1) output has a few seconds of delay and the heated oxygen sensor (sensor 2) output has a maximum of 20 seconds of delay.

If the vehicle is short on fuel, the air-fuel ratio becomes LEAN and the DTCs will be recorded.

A0019VQE08

Tech Tips


  • Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.


  • Bank 1 refers to the bank that includes No. 1 cylinder.

  • Bank 2 refers to the bank that does not include No. 1 cylinder.

  • No. 1 cylinder is located in the front part of the engine, opposite the transmission.

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

PROCEDURE


  1. CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0136, P0156)


    1. Connect the intelligent tester to the DLC3.

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

    3. Enter the following menus: Powertrain / Engine / DTC.

    4. Read the DTCs.

      Result
      Display (DTC output) Proceed to
      P0136 or P0156 A
      P0136 or P0156 and other DTCs B

      Tech Tips

      If any other codes besides P0136 and P0156 are output, perform the troubleshooting for those DTCs first.


    B

    GO TO RELEVANT CHART Click here

    A

  2. READ DATA LIST (HEATED OXYGEN SENSOR (SENSOR 2) VOLTAGE)


    1. Connect the intelligent tester to the DLC3.

    2. Enter the following menus: Powertrain / Engine / Data List / Primary / O2S B1 S2 (or O2S B2 S2).

    3. Allow the engine to run at 2500 rpm for 3 minutes.

    4. Depress the accelerator pedal quickly until the engine rpm reaches 4000 rpm 3 times.

      Standard voltage
      The heated oxygen sensor voltage alternates from below 0.4 V to 0.5 V or more.

    OK

    PERFORM CONFIRMATION DRIVING PATTERN Click here

    NG

  3. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

    A001EB5E27

    1. Disconnect the L49 and L50 sensor connectors.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      1 (HT1B) - 2 (+B) Always 11 to 16 Ω
      1 (HT2B) - 2 (+B) Always 11 to 16 Ω
      1 (HT1B) - 4 (E2) Always 10 kΩ or higher
      1 (HT2B) - 4 (E2) Always 10 kΩ or higher

    NG

    REPLACE HEATED OXYGEN SENSOR Click here

    OK

  4. INSPECT EFI RELAY (EFI MAIN2)

    A001BUF

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

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

      Standard resistance
      Tester Connections Condition Specified Condition
      3 - 5 When no battery voltage is applied to terminals 1 and 2 10 kΩ or higher
      When battery voltage is applied to terminals 1 and 2 Below 1 Ω

    NG

    REPLACE EFI RELAY (EFI MAIN2)

    OK

  5. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR (SENSOR 2) - ECM)

    A001BWAE02

    1. Disconnect the L49 and L50 sensor connectors.

    2. Disconnect the A13 and E1 ECM connectors.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      L50-1 (HT1B) - A13-4 (HT1B) Always Below 1 Ω
      L49-1 (HT2B) - A13-3 (HT2B) Always Below 1 Ω
      L50-3 (OX1B) - A13-26 (OX1B) Always Below 1 Ω
      L49-3 (OX2B) - A13-27 (OX2B) Always Below 1 Ω
      L50-4 (E2) - E1-28 (E2) Always Below 1 Ω
      L49-4 (E2) - E1-28 (E2) Always Below 1 Ω
      L50-1 (HT1B) or A13-4 (HT1B) - Body ground Always 10 kΩ or higher
      L49-1 (HT2B) or A13-3 (HT2B) - Body ground Always 10 kΩ or higher
      L50-3 (OX1B) or A13-26 (OX1B) - Body ground Always 10 kΩ or higher
      L49-3 (OX2B) or A13-27 (OX2B) - Body ground Always 10 kΩ or higher

    OK

    REPLACE HEATED OXYGEN SENSOR Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. PERFORM CONFIRMATION DRIVING PATTERN

    Tech Tips

    Clear all DTCs before performing the confirmation driving pattern.


    NEXT

  7. READ OUTPUT DTC (DTC P0136 OR P0156 IS OUTPUT AGAIN)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester ON.

    4. Start the engine and allow the engine to idle for 15 seconds or more.

    5. Enter the following menus: Powertrain / Engine / DTC / Pending Codes.

    6. Read the DTC.

      Result
      Display (DTC output) Proceed to
      P0136 or P0156 A
      No output B

    A

    REPLACE HEATED OXYGEN SENSOR Click here

    B

    CHECK FOR INTERMITTENT PROBLEMS Click here