2GR-FE Engine Control System Oxygen Sensor Manual

ES–108

DTC

DTC

DTC

DTC

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

P0031

P0032

P0051

P0052

Oxygen (A/F) Sensor Heater Control Circuit

Low (Bank 1 Sensor 1)

Oxygen (A/F) Sensor Heater Control Circuit

High (Bank 1 Sensor 1)

Oxygen (A/F) Sensor Heater Control Circuit

Low (Bank 2 Sensor 1)

Oxygen (A/F) Sensor Heater Control Circuit

High (Bank 2 Sensor 1)

ES

DESCRIPTION

Refer to DTC P2195 (see page ES-334 ).

HINT:

• Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.

• Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

• When one of these DTCs is set, the ECM enters fail-safe mode. The ECM turns off the A/F sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned OFF.

• The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The

A/F sensor heater circuit uses a relay on the B+ side of the circuit.

Reference (System Diagram of Bank 1 Sensor 1):

A/F Sensor

ECM

A/F from

Battery

+B

Heater

HA1A HA1A

A/F

A1A-

Sensor

A1A+ A1A+

A1Afrom

EFI MAIN

Relay EFI NO. 2

A137606E01

DTC No.

P0031

P0051

DTC Detection Condition

Air-Fuel Ratio (A/F) sensor heater current less than 0.8 A

(1 trip detection logic)

Trouble Area

• Open in A/F sensor heater circuit

• A/F sensor heater (sensor 1)

• Integration relay

• ECM

ES–109

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

DTC No.

P0032

P0052

DTC Detection Condition

Air-Fuel Ratio (A/F) sensor heater current fail

(1 trip detection logic)

Trouble Area

• Short in A/F sensor heater circuit

• A/F sensor heater (sensor 1)

• Integration relay

• ECM

HINT:

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

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

• Sensor 1 refers to the sensor closest to the engine assembly.

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

MONITOR DESCRIPTION

The ECM uses information from the Air-Fuel Ratio (A/F) sensor to regulate the air-fuel ratio and keep it close to the stoichiometric level. This maximizes the ability of the Three-Way Catalytic Converter (TWC) to purify the exhaust gases.

The A/F sensor detects oxygen levels in the exhaust gas and transmits the information to the ECM. The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of platinum coated zirconia and includes an integrated heating element.

The zirconia element generates a small voltage when there is a large difference in the oxygen concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage generation.

The A/F sensor is more efficient when heated. When the exhaust gas temperature is low, the sensor cannot generate useful voltage signals without supplementary heating. The ECM regulates the supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater element. If the heater current is outside the normal range, the signal transmitted by the A/F sensor becomes inaccurate. As a result, the ECM is unable to regulate air-fuel ratio properly.

When the current in the A/F sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and sets a DTC.

Example:

The ECM sets DTC P0032 or P0052 when the current in the A/F sensor heater is more than 10 A.

Conversely, when the heater current is less than 0.8 A, DTC P0031 or P0051 is set.

ES

MONITOR STRATEGY

Related DTCs

Required Sensors/Components (Main)

Required Sensors/Components (Related)

Frequency of Operation

Duration

MIL Operation

Sequence of Operation

P0031: A/F sensor heater (bank 1) open/short (Low electrical current)

P0032: A/F sensor heater (bank 1) open/short (High electrical current)

P0051: A/F sensor heater (bank 2) open/short (Low electrical current)

P0052: A/F sensor heater (bank 2) open/short (High electrical current)

A/F sensor heater

-

Continuous

10 seconds

Immediate

None

TYPICAL ENABLING CONDITIONS

All:

Monitor runs whenever following DTCs not present

P0031 and P0051:

Battery voltage

A/F sensor heater duty-cycle ratio

Time after engine start

None

10.5 V or more

50% or more

10 seconds or more

ES–110

P0032 and P0052:

Time after engine start

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

10 seconds or more

TYPICAL MALFUNCTION THRESHOLDS

P0031 and P0051:

A/F sensor heater current Less than 0.8 A

P0032 and P0052:

Hybrid IC high current limiter port Fail

COMPONENT OPERATING RANGE

A/F sensor heater current

ES

WIRING DIAGRAM

Refer to DTC P2195 (see page ES-339 ).

0.9 to 9.9 A

INSPECTION PROCEDURE

HINT:

Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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 AIR-FUEL RATIO SENSOR (HEATER RESISTANCE)

Component Side:

+B

A/F Sensor

B48 Bank 1

B33 Bank 2

A1A-

A2A-

HA1A

HA2A

A1A+

A2A+

A052607E30

(a) Disconnect the B33 or B48 A/F sensor connector.

(b) Measure the resistance of the A/F sensor connector.

Standard resistance

Bank 1

Tester Connection

1 (HA1A) - 2 (+B)

1 (HA1A) - 4(A1A-)

Specified Condition

20

°C (68°F)

-

Specified Condition

1.8 to 3.4

Ω

10 k

Ω or higher

Standard resistance

Bank 2

Tester Connection

1 (HA2A) - 2 (+B)

Specified Condition

20

°C (68°F)

1 (HA2A) - 4 (A2A-) -

Specified Condition

1.8 to 3.4

Ω

10 k

Ω or higher

(c) Reconnect the A/F sensor connector.

NG REPLACE AIR-FUEL RATIO SENSOR

OK

ES–111

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

2 CHECK TERMINAL VOLTAGE (+B OF A/F SENSOR)

Wire Harness Side:

B48 Bank 1

B33 Bank 2

A/F Sensor

+B

A076787E12

(a) Disconnect the B33 or B48 A/F sensor connector.

(b) Turn the ignition switch ON.

(c) Measure the voltage between the terminals of the B33 or

B48 A/F sensor connector and body ground.

Standard voltage

Tester Connection

B33-2 (+B) - Body ground

B48-2 (+B) - Body ground

Specified Condition

9 to 14 V

9 to 14 V

(d) Reconnect the A/F sensor connector.

OK Go to step 5 ES

NG

3 INSPECT INTEGRATION RELAY (A/F RELAY)

Integration Relay

Fuse Side:

1

2

A/F

Connector Side:

1C

1

1B

8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1

A107921E15

(a) Remove the integration relay from the engine room No. 1 relay block.

(b) Inspect the A/F fuse.

(1) Remove the A/F fuse from the integration relay.

(2) Measure the A/F fuse resistance.

Standard resistance:

Below 1

Ω

(3) Reinstall the A/F fuse.

(c) Inspect the A/F relay.

(1) Measure the A/F relay resistance.

Standard resistance

Tester Connection

1C-1 - 1B-8

Specified Condition

10 k

Ω or higher

Below 1

Ω

(Apply battery voltage between terminals 1B-6 and 1B-7)

(d) Reinstall the integration relay.

NG REPLACE INTEGRATION RELAY

OK

ES–112

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

ES

4 CHECK WIRE HARNESS (INTEGRATION RELAY - A/F SENSOR AND BODY GROUND)

Wire Harness Side:

B48 Bank 1

B33 Bank 2

A/F Sensor

Integration Relay

8 7 6

1B

+B

1A

4

Engine Room

No. 1 Relay

Block

(a) Check the EFI NO. 2 fuse.

(b) Disconnect the B33 or B48 A/F sensor connector.

(c) Remove the integration relay from the engine room No. 1 relay block.

(d) Measure the resistance.

Standard resistance

Tester Connection

B48-2 (+B) - 1B-8

B33-2 (+B) - 1B-8

1A-4 - 1B-6

1B-7 - Body ground

B48-2 (+B) or 1B-8 - Body ground

B33-2 (+B) or 1B-8 - Body ground

1A-4 or 1B-6 - Body ground

Specified Condition

Below 1

Ω

Below 1

Ω

Below 1

Ω

Below 1

Ω

10 k

Ω or higher

10 k

Ω or higher

10 k

Ω or higher

(e) Reconnect the A/F sensor connector.

(f) Reinstall the integration relay.

NG REPAIR OR REPLACE HARNESS AND

CONNECTOR

EFI NO. 2

A127733E04

OK

CHECK ECM POWER SOURCE CIRCUIT

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM

5 CHECK WIRE HARNESS (A/F SENSOR - ECM)

Wire Harness Side:

B48 HA1A

Bank 1

B33 HA2A

Bank 2

A/F Sensor

B30 ECM

(a) Disconnect the B33 or B48 A/F sensor connector.

(b) Disconnect the B30 ECM connector.

(c) Measure the resistance.

Standard resistance

Tester Connection

B48-1 (HA1A) - B30-86 (HA1A)

B33-1 (HA2A) - B30-109 (HA2A)

B48-1 (HA1A) or B30-86 (HA1A) -

Body ground

B33-1 (HA2A) or B30-109 (HA2A) -

Body ground

Specified Condition

Below 1

Ω

Below 1

Ω

10 k

Ω or higher

10 k

Ω or higher

(d) Reconnect the A/F sensor connector.

(e) Reconnect the ECM connector.

NG REPAIR OR REPLACE HARNESS AND

CONNECTOR

ES–113

ES

HA2A HA1A

A127715E09

OK

6 CHECK WHETHER DTC OUTPUT RECURS

(a) Connect the intelligent tester to the DLC3.

(b) Turn the ignition switch ON.

(c) Turn the tester ON.

(d) Clear DTCs (see page ES-39 ).

(e) Start the engine.

(f) Allow the engine to idle for 1 minute or more.

(g) Select the following menu items: DIAGNOSIS /

ENHANCED OBD II / DTC INFO / CURRENT CODES.

(h) Read DTCs.

Result

Display (DTC Output)

No output

P0031, P0032, P0051 or P0052

Proceed to

A

B

B REPLACE ECM

A

CHECK FOR INTERMITTENT PROBLEMS