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

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

for Preparation Click here


DESCRIPTION

  1. Refer to DTC P0136 (Click here).

HINT:
  1. Sensor 2 refers to the sensor mounted behind the three-way catalytic converter 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 ignition switch is turned off.

  3. The ECM provides a pulse width modulated signal to the 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.


    A201297E01


DTC No.
DTC Detection Condition
Trouble Area
P0037
Heated oxygen sensor heater current less than 0.3 A
(1-trip detection logic)
  1. Open in heated oxygen sensor heater circuit
  2. Heated oxygen sensor (sensor 2)
  3. Integration relay (EFI relay)
  4. ECM
P0038
Heated oxygen sensor heater current more than 2 A
(1-trip detection logic)
  1. Short in heated oxygen sensor heater circuit
  2. Heated oxygen sensor (sensor 2)
  3. Integration relay (EFI relay)
  4. ECM


WIRING DIAGRAM

Refer to DTC P0136 (Click here).

INSPECTION PROCEDURE

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

HINT:
Read freeze frame data using an 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 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.

1.INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)


    A200916E01

  1. Disconnect the heated oxygen sensor connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    1 (HT1B) - 2 (+B)
    		20°C (68°F)
    		11 to 16 Ω
    1 (HT1B) - 4 (E2)
    		Always
    		10 kΩ or higher

    Text in Illustration 
    *1
    		Component without harness connected:
    (Heated Oxygen Sensor)

  1. Reconnect the heated oxygen sensor connector.



NG
REPLACE HEATED OXYGEN SENSOR (Click here)
OK


2.CHECK TERMINAL VOLTAGE (POWER SOURCE)
A200917E01

  1. Disconnect the heated oxygen sensor connector.

  1. Turn the ignition switch to ON.

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    B19-2 (+B)*2 - Body ground
    		Ignition switch ON
    		11 to 14 V
    B20-2 (+B)*3 - Body ground
    		Ignition switch ON
    		11 to 14 V

    Text in Illustration 
    *1
    		Front view of wire harness connector:
    (to Heated Oxygen Sensor)
    *2
    		for CVT
    *3
    		for Manual Transaxle

  1. Reconnect the heated oxygen sensor connector.



NG
Go to step 4
OK


3.CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)
A200841E01

  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 (Check for Open):
    Tester Connection
    		Condition
    		Specified Condition
    B19-1 (HT1B)*3 - B8-63 (HT1B)
    		Always
    		Below 1 Ω
    B20-1 (HT1B)*4 - B8-63 (HT1B)
    		Always
    		Below 1 Ω

    Standard Resistance (Check for Short):
    Tester Connection
    		Condition
    		Specified Condition
    B19-1 (HT1B)*3 or B8-63 (HT1B) - Body ground
    		Always
    		10 kΩ or higher
    B20-1 (HT1B)*4 or B8-63 (HT1B) - Body ground
    		Always
    		10 kΩ or higher

    Text in Illustration 
    *1
    		Front view of wire harness connector:
    (to Heated Oxygen Sensor)
    *2
    		Front view of wire harness connector:
    (to ECM)
    *3
    		for CVT
    *4
    		for Manual Transaxle

  1. Reconnect the heated oxygen sensor connector.

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ECM (Click here)  

4.CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - INTEGRATION RELAY)
A201298E01

  1. Disconnect the heated oxygen sensor connector.

  1. Remove the integration relay (EFI relay) from the engine room relay block and junction block.

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

    Standard Resistance (Check for Open):
    Tester Connection
    		Condition
    		Specified Condition
    B19-2 (+B)*3 - 1F-12
    		Always
    		Below 1 Ω
    B20-2 (+B)*4 - 1F-12
    		Always
    		Below 1 Ω

    Standard Resistance (Check for Short):
    Tester Connection
    		Condition
    		Specified Condition
    B19-2 (+B)*3 or 1F-12 - Body ground
    		Always
    		10 kΩ or higher
    B20-2 (+B)*4 or 1F-12 - Body ground
    		Always
    		10 kΩ or higher

    Text in Illustration 
    *1
    		Front view of wire harness connector:
    (to Heated Oxygen Sensor)
    *2
    		Front view of wire harness connector:
    (to Integration Relay)
    *3
    		for CVT
    *4
    		for Manual Transaxle

  1. Reconnect the heated oxygen sensor connector.

  1. Reinstall the integration relay.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPAIR OR REPLACE ECM POWER SOURCE CIRCUIT (Click here)