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P0037 P0038 P102D

DTC    P0037    Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)

DTC    P0038    Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 2)

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


 

DESCRIPTION

Refer to DTC P0136.
 

HINT:
  1. Sensor 2 refers to the sensor mounted behind the Three-way Catalytic Converter (TWC) and located far from the engine assembly.
  2. When any of these DTCs are set, 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 power switch is turned off.

  3. The ECM uses pulse width modulation to adjust the current through the heater. The heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.
     

    P0037 P0038 P102D / Lexus CT200h / ZWA10

 

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).
  1. Open in heated oxygen sensor (sensor 2) heater circuit
  2. Heated oxygen sensor (sensor 2) heater
  3. ECM
P0038 The heater current is higher than the specified value while the heater is operating (1 trip detection logic).
  1. Short in heated oxygen sensor (sensor 2) heater circuit
  2. Heated oxygen sensor (sensor 2) heater
  3. 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.

  1. Heated Oxygen Sensor Heater Range Check (P0037, P0038 and P102D):
    1. 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.

 

MONITOR STRATEGY

 

Frequency of operation Continuous

 

TYPICAL ENABLING CONDITIONS

P0037, P0038, P102D 

Time after heater ON 10 seconds or more

HINT:

When the values for Data List items O2 Heater Curr Val B1S2 are not 0 A, the heater is on.

CONFIRMATION DRIVING PATTERN


P0037 P0038 P102D / Lexus CT200h / ZWA10

 

  1. Connect the intelligent tester to the DLC3.
  2. Turn the power switch on (IG) and turn the tester on.
  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).
  4. Turn the power switch off and wait for 30 seconds.
  5. Turn the power switch on (IG) and turn the tester on [A].
  6. Put the engine in inspection mode (maintenance mode).
  7. Start the engine and idle it for 5 minutes or more [B].
  8. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 2500 rpm for 1 minute [C].
  9. Idle the engine for 5 minutes or more [D].
  10. Enter the following menus: Powertrain / Engine and ECT / DTC.
  11. Read the DTC [E].

    HINT:

    1. If a DTC is output, the system is malfunctioning.
    2. If a DTC is not output, perform the following procedure.

     

  12. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
  13. Input the DTC: P0037, P0038 or P102D.
  14. Check the DTC judgment result.
     
    Tester Display Description
    NORMAL
    1. DTC judgment completed
    2. System normal
    ABNORMAL
    1. DTC judgment completed
    2. System abnormal
    INCOMPLETE
    1. DTC judgment not completed
    2. Perform driving pattern after confirming DTC enabling conditions
    UNKNOWN
    1. Unable to perform DTC judgment
    2. Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    HINT:

    1. If the judgment result shows NORMAL, the system is normal.
    2. If the judgment result shows ABNORMAL, the system has a malfunction.
    3. If the judgment result shows INCOMPLETE or UNKNOWN, perform step [B] through [E] again.

WIRING DIAGRAM

Refer to DTC P0136.
 

INSPECTION PROCEDURE

NOTICE:

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

HINT:

  1. Refer to "Data List / Active Test" [O2 Heater B1S2 and O2 Heater Curr Val B1S2].
  2. Sensor 1 refers to the sensor closest to the engine assembly.
  3. Sensor 2 refers to the sensor farthest away from the engine assembly.
  4. Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
1.INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
  1. Inspect the heated oxygen sensor.

  NG
REPLACE HEATED OXYGEN SENSOR
 
OK  
 

 

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


 

P0037 P0038 P102D / Lexus CT200h / ZWA10
  1. Disconnect the heated oxygen sensor connector.

  1. Turn the power switch on (IG).

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

    Standard Voltage:

    Tester Connection Switch Condition Specified Condition
    D9-2 (+B) - Body ground Power switch on (IG) 11 to 14 V
    Text in Illustration 
    *a Front view of harness connector
    ( to Heated Oxygen Sensor (Sensor 2))
  NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (HEATED OXYGEN SENSOR - EFI MAIN RELAY)
 
OK  
 

 

3.CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)
  1. Disconnect the heated oxygen sensor connector.

  1. Disconnect the ECM connector.

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

    Standard Resistance:

     
    Tester Connection Condition Specified Condition
    D9-1 (HT1B) - D27-41 (HT1B) Always Below 1 Ω
    D9-1 (HT1B) or D27-41 (HT1B) - Body ground Always 10 kΩ or higher
  NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
 
OK  
 

 

4.CHECK WHETHER DTC OUTPUT RECURS (DTC P0037, P0038 OR P0102D)
  1. Connect the intelligent tester to the DLC3.

  1. Turn the power switch on (IG).

  1. Turn the tester on.

  1. Clear the DTCs.

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

  1. Enter the following menus: Powertrain / Engine and ECT / DTC.

  1. Read the DTCs.

    Result 
    Result Proceed to
    DTC is not output A
    DTC P0037, P0038 or P102D is output B
  B
REPLACE ECM
 
A  
 
CHECK FOR INTERMITTENT PROBLEMS