DTC P0031: Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1); DTC P0032: Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1): Procedure

1. Disconnect the air fuel ratio sensor connector.
   Fig 1: Identifying Air Fuel Ratio Sensor Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1 (HA1A) - 2 (+B)	20°C (68°F)	1.8 to 3.4 Ω
   1 (HA1A) - 4 (A1A-)	Always	10 kΩ or higher

3. Reconnect the air fuel ratio sensor connector.

NG → See step   6 

OK: Go to next step 

1. Disconnect the air fuel ratio sensor connector.
   Fig 2: Identifying B37 Air Fuel Ratio Sensor Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the ignition switch to ON.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   B37-2 (+B) - Body ground	Ignition switch ON	11 to 14 V

4. Reconnect the air fuel ratio sensor connector.

NG → See step   5 

OK: Go to next step 

1. Disconnect the air fuel ratio sensor connector.
   Fig 3: Identifying Air Fuel Ratio Sensor Connector And ECM Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the ECM connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance (Check for Open)

   Tester Connection	Condition	Specified Condition
   B37-1 (HA1A) - B29-109 (HA1A)	Always	Below 1 Ω

   Standard Resistance (Check for Short)

   Tester Connection	Condition	Specified Condition
   B37-1 (HA1A) or B29-109 (HA1A) - Body ground	Always	10 kΩ or higher

4. Reconnect the air fuel ratio sensor connector.
5. Reconnect the ECM connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ECM) 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear DTCs . Refer to DTC CHECK / CLEAR .
5. Start the engine.
6. Allow the engine to idle for 1 minute or more.
7. Select the following menus: Powertrain / Engine and ECT / Trouble Codes.
8. Read the DTCs.

   Result

   Result	Proceed to
   DTC is not output	A
   DTC P0031 or P0032 is output	B

B → See step   7 

A → See step   8 

1. Remove the EFI No. 2 fuse from the engine room relay block.
   Fig 4: Identifying EFI No. 2 Fuse

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   EFI No. 2 fuse	Always	Below 1 Ω

3. Reinstall the EFI No. 2 fuse.

NG → REPLACE FUSE (EFI NO. 2) 

OK → REPAIR OR REPLACE HARNESS OR CONNECTOR (INTEGRATION RELAY (EFI MAIN RELAY) - AIR FUEL RATIO SENSOR)