DTC P0031 Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 1) : DTC P0032 Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 1): Wiring Diagram

WARNING: This page is about a different car, the 2006 Scion tC. However, it is still accessible from the selected car via links, so may be relevant.

Refer to DTC P2195 ).

HINT:

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.

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Disconnect the A3 Air-Fuel Ratio (A/F) sensor connector.
Measure the resistance of the A/F sensor.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

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

NG : REPLACE AIR FUEL RATIO SENSOR

Fig 1: Identifying A3 Air-Fuel Ratio Sensor Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INSPECT EFI RELAY (Marking: EFI)

Remove the EFI relay from the engine room relay block.
Measure the EFI relay resistance of the relay.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
3 - 5	10 kΩ or higher
3 - 5	Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

NG : REPLACE EFI RELAY

Fig 2: Inspecting EFI Relay (Marking - EFI)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK : Go to next step

INSPECT ECM (HT1A VOLTAGE)

Turn the ignition switch ON.
Measure the voltage of the ECM connector.

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
HA1A (E7-5) - E04 (E7-7)	9 to 14 V

NG : GO TO STEP 4

Fig 3: Identifying ECM Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK : REPLACE ECM

CHECK WIRE HARNESS (AIR FUEL RATIO SENSOR - ECM, AIR FUEL RATIO SENSOR - EFI RELAY)

Check the wire harness between the ECM and A/F sensor.

Disconnect the A3 A/F sensor connector.
Disconnect the E7 ECM connector.
Measure the resistance of the wire harness side connector.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
HT (A3-1) - HA1A (E7-5)	Below 1 Ω
HT (A3-1) or HA1A (E7-5) - Body ground	10 kΩ or higher

Check the wire harness between the A/F sensor and EFI relay.
1. Disconnect the A3 A/F sensor connector.
2. Remove the EFI relay from the engine room relay block.
3. Measure the resistance of the wire harness side connector.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
+B (A3-2) - EFI relay (3)	Below 1 Ω
+B (A3-2) or EFI relay (3) - Body ground	10 kΩ or higher

NG : REPAIR OR REPLACE HARNESS AND CONNECTOR

Fig 4: Disconnecting A3 A/F Sensor Connector

OK : REPLACE ECM