2NZ-FE ENGINE CONTROL SFI SYSTEM P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) P0032 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1)

DESCRIPTION

The heated oxygen sensor is used to monitor the oxygen concentration in the exhaust gas. For optimum catalytic converter operation, the air fuel mixture must be maintained near the ideal stoichiometric air fuel ratio. The heated oxygen sensor output voltage changes suddenly in the vicinity of the stoichiometric air fuel ratio. The ECM adjusts the fuel injection time so that the air fuel ratio is nearly stoichiometric. The heated oxygen sensor generates a voltage between 0 and 1 V in response to the oxygen concentration in the exhaust gas.

If the oxygen concentration in the exhaust gas increases, the air fuel ratio is described as lean. The heated oxygen sensor voltage drops to below 0.45 V and the heated oxygen sensor informs the ECM of the lean condition. If there is little oxygen in the exhaust gas, the air fuel ratio is described as rich. The heated oxygen sensor voltage increases to above 0.45 V and the heated oxygen sensor informs the ECM of the rich condition.

0.948,2.385 0.656,2.385 false 3.375,0.406 3.115,0.646 false 3.427,1.031 2.885,1.031 true 3.427,0.719 2.854,0.906 true 3.427,1.625 2.906,1.479 false 3.427,1.927 2.771,1.698 true 3.427,2.208 2.875,1.896 true 2.323,2.115 1.771,2.427 true 0.24,2.313 0.667,2.479 0.427,0.167 10 false Cover 1.313,2.438 2.198,2.615 0.885,0.177 10 false Exhaust Gas 1.865,0.26 2.719,0.458 0.854,0.198 10 false Atmosphere 3.396,0.344 3.979,0.552 0.583,0.208 10 false Housing 3.448,0.667 4.688,0.833 1.24,0.167 10 false Platinum Electrode 3.448,0.969 4.667,1.323 1.219,0.354 10 false Solid Electrolyte (Zirconia Element) 3.448,1.865 3.958,2.042 0.51,0.177 10 false Heater 3.448,2.146 4.635,2.354 1.188,0.208 10 false Coating (Ceramic) 3.448,1.563 4.688,1.729 1.24,0.167 10 false Platinum Electrode 4.115,0.333 5.094,0.531 0.979,0.198 10 false Output Voltage 4.792,2.25 6.833,2.469 2.042,0.219 10 false Richer - Air Fuel Ratio - Leaner 5.115,0.177 6.479,0.385 1.365,0.208 10 false Ideal Air Fuel Mixture

4.563,1.521 5.094,1.896 0.531,0.375 10 false OX1A 4.563,0.948 5.073,1.396 0.51,0.448 10 false HT1A 5.167,2.667 5.698,2.958 0.531,0.292 10 false MREL 5.167,2.094 5.708,2.479 0.542,0.385 10 false EX1A 5.167,1.51 5.688,1.844 0.521,0.333 10 false OX1A 5.167,0.948 5.656,1.24 0.49,0.292 10 false HT1A 3.896,0.792 4.344,0.948 0.448,0.156 10 false Heater 3.885,1.302 4.344,1.458 0.458,0.156 10 false Sensor 2.313,2.375 3.021,2.604 0.708,0.229 10 false EFI 0.208,1.073 0.99,1.302 0.781,0.229 10 false from Battery 1.094,1.219 1.76,1.365 0.667,0.146 10 false EFI-MAIN 0.958,3.406 1.458,3.573 0.5,0.167 10 false Ground 3.469,2 5.021,2.438 1.552,0.438 10 false Heated Oxygen Sensor 3.448,1.51 3.656,1.656 0.208,0.146 10 false E2 3.448,0.958 3.646,1.104 0.198,0.146 10 false +B 0.156,0.219 2.625,0.406 2.469,0.188 10 false System Diagram: 5.948,3.344 6.313,3.5 0.365,0.156 10 false ECM 2.927,1.25 3.625,1.458 0.698,0.208 10 false EFI NO. 2

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P0031	Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)	Heated oxygen sensor heater current below 0.25 A when heater operates with +B greater than 10.5 V (1 trip detection logic).	· Open in Heated oxygen sensor heater circuit · Heated oxygen sensor · ECM	Comes on	DTC stored
P0032	Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1)	Heated oxygen sensor heater current exceeds 2 A when heater operates (1 trip detection logic).	· Short in Heated oxygen sensor heater circuit · Heated oxygen sensor · ECM	Comes on	DTC stored

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. If the zirconia element is at the proper temperature and the difference in the oxygen concentration between the inside and outside surface of the sensor is large, the zirconia element will generate voltage signals. In order to increase the oxygen concentration detecting capacity in the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor. When the current in the heated oxygen sensor heater is out of the standard operating range, the ECM interprets this as a fault in the heated oxygen sensor heater. The ECM illuminates the MIL and stores a DTC.

MONITOR STRATEGY

Required Sensors/Components (Main)	Heated oxygen sensor heater
Required Sensors/Components (Related)	Vehicle speed sensor
Frequency of Operation	Continuous

TYPICAL ENABLING CONDITIONS

Battery voltage	10.5 V or higher
Engine	Running
Starter	OFF

Duration of following conditions	2 seconds or more
Learned heater current during heater OFF	Completed

TYPICAL MALFUNCTION THRESHOLDS

Heated oxygen sensor heater current when heated oxygen sensor heater ON

Less than 0.25 A

CONFIRMATION DRIVING PATTERN

0.75,0.969 1.396,1.167 0.646,0.198 10 false 3000 rpm 0.948,1.74 1.354,1.896 0.406,0.156 10 false Idling 0.208,2.01 1.417,2.354 1.208,0.344 10 false Ignition Switch ON 1.927,2.135 2.167,2.302 0.24,0.167 10 false [A] 2.76,1.625 2.958,1.823 0.198,0.198 10 false [B] 4.021,0.865 4.281,1.094 0.26,0.229 10 false [C] 5.385,1.604 5.604,1.781 0.219,0.177 10 false [D] 2.271,2.594 3.469,2.75 1.198,0.156 10 false 5 minutes or more 4.875,2.604 6.073,2.76 1.198,0.156 10 false 5 minutes or more 3.854,2.615 4.427,2.781 0.573,0.167 10 false 1 minute 5.979,3.031 6.177,3.229 0.198,0.198 10 false [E]

Connect the GTS to the DLC3.

Turn the ignition switch to ON and turn the GTS on.

Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON and turn the GTS on [A].

Start the engine and idle it for 5 minutes or more [B].

With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 3000 rpm for 1 minute [C].

Idle the engine for 5 minutes or more [D].

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].

10.

Read DTCs.

HINT:: ·

If a DTC is output, the system is malfunctioning.

·

If a DTC is not output, perform the following procedure.

11.

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

12.

Input the DTC: P0031 or P0032.

13.

Check the DTC judgment result.

GTS Display	Description
NORMAL	· DTC judgment completed · System normal
ABNORMAL	· DTC judgment completed · System abnormal
INCOMPLETE	· DTC judgment not completed · Perform driving pattern after confirming DTC enabling conditions
N/A	· Unable to perform DTC judgment · Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:: ·

If the judgment result shows NORMAL, the system is normal.

·

If the judgment result shows ABNORMAL, the system has a malfunction.

·

If the judgment result shows INCOMPLETE or N/A, perform steps [B] through [E] again.

WIRING DIAGRAM

0.698,3.927 1.604,4.271 0.906,0.344 10 false Battery 0.573,2.646 1.354,2.906 0.781,0.26 10 false FL MAIN 0.552,1.24 1.271,1.5 0.719,0.26 10 false EFI-MAIN 1.406,1.583 2.125,1.854 0.719,0.271 10 false EFI-MAIN 1.313,0.406 1.469,0.604 0.156,0.198 10 false 5 1.313,1.146 1.469,1.344 0.156,0.198 10 false 2 2.042,0.396 2.198,0.594 0.156,0.198 10 false 3 2.031,1.156 2.188,1.354 0.156,0.198 10 false 1 2.531,0.677 3.427,0.969 0.896,0.292 10 false EFI NO. 2 3.771,0.385 3.927,0.583 0.156,0.198 10 false 2 3.927,0.396 4.188,0.625 0.26,0.229 10 false +B 3.781,1.135 3.938,1.333 0.156,0.198 10 false 4 3.927,1.135 4.198,1.375 0.271,0.24 10 false E2 4.51,0.396 5.042,0.646 0.531,0.25 10 false HT1A 4.927,0.396 5.083,0.625 0.156,0.229 10 false 1 4.49,1.063 4.948,1.281 0.458,0.219 10 false OX1A 4.906,1.135 5.063,1.333 0.156,0.198 10 false 3 3.625,1.635 4.083,1.833 0.458,0.198 10 false B58 3.615,1.823 5.125,2.135 1.51,0.313 10 false Heated Oxygen Sensor 5.385,1.042 5.542,1.24 0.156,0.198 10 false * 6.271,0.49 6.792,0.74 0.521,0.25 10 false HT1A 5.927,0.5 6.302,0.729 0.375,0.229 10 false B56 5.927,0.313 6.323,0.552 0.396,0.24 10 false 109 5.927,1.24 6.333,1.469 0.406,0.229 10 false B56 5.927,1.052 6.385,1.25 0.458,0.198 10 false 112 6.26,1.24 6.813,1.479 0.552,0.24 10 false OX1A 5.938,2.656 6.396,2.854 0.458,0.198 10 false B56 5.99,2.458 6.302,2.656 0.313,0.198 10 false 90 6.271,2.667 6.823,2.927 0.552,0.26 10 false EX1A 5.948,3.375 6.406,3.573 0.458,0.198 10 false A56 6.25,3.375 6.708,3.615 0.458,0.24 10 false MREL 5.99,3.188 6.302,3.385 0.313,0.198 10 false 44 6.406,4.073 6.844,4.344 0.438,0.271 10 false ECM 1.49,3.771 2.563,4.156 1.073,0.385 10 false *: Shielded

CAUTION / NOTICE / HINT

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

HINT:: ·

Read freeze frame data using the GTS. 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.

·

Change the fuel injection volume using the Control the Injection Volume for A/F sensor function provided in the Active Test and monitor the heated oxygen sensor output voltage. If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

Click hereEngine / Hybrid System>2NZ-FE ENGINE CONTROL>SFI SYSTEM>P0132

PROCEDURE

1.INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

Inspect the heated oxygen sensor.

Click hereEngine / Hybrid System>2NZ-FE ENGINE CONTROL>HEATED OXYGEN SENSOR>INSPECTION

Result:

Proceed to
OK
NG

2.CHECK TERMINAL VOLTAGE (POWER SOURCE OF HEATED OXYGEN SENSOR)

REPLACE HEATED OXYGEN SENSOR

Click hereEngine / Hybrid System>2NZ-FE ENGINE CONTROL>HEATED OXYGEN SENSOR>REMOVAL

2.CHECK TERMINAL VOLTAGE (POWER SOURCE OF HEATED OXYGEN SENSOR)

0.635,1.979 1.125,2.271 0.49,0.292 1.969,2.042 2.542,1.865 false 0.208,0.281 0.469,0.49 0.26,0.208 10 false *a 2.583,1.771 2.802,1.948 0.219,0.177 10 false +B 0.76,2.042 1.094,2.198 0.333,0.156 10 false B58

*a	Front view of wire harness connector (to Heated Oxygen Sensor)

Disconnect the heated oxygen sensor connector.

Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
B58-2 (+B) - Body ground	Ignition switch ON	11 to 14 V

Result:

Proceed to
OK
NG

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

REPAIR OR REPLACE HARNESS OR CONNECTOR (HEATED OXYGEN SENSOR - EFI-MAIN RELAY)

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

Disconnect the heated oxygen sensor connector.

Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
B58-1 (HT1A) - B56-109 (HT1A)	Always	Below 1 Ω
B58-1 (HT1A) or B56-109 (HT1A) - Body ground	Always	10 kΩ or higher

Result:

Proceed to
OK
NG

4.CHECK WHETHER DTC OUTPUT RECURS (DTC P0031 OR P0032)

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.CHECK WHETHER DTC OUTPUT RECURS (DTC P0031 OR P0032)

Connect the GTS to the DLC3.

Turn the ignition switch to ON.

Turn the GTS on.

Clear the DTCs.

Powertrain > Engine and ECT > Clear DTCs: 50002 234

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON.

Turn the GTS on.

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

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

Read the DTCs.

Powertrain > Engine and ECT > Trouble Codes: 50001 234

Result:

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

CHECK FOR INTERMITTENT PROBLEMS

Click hereEngine / Hybrid System>2NZ-FE ENGINE CONTROL>SFI SYSTEM>CHECK FOR INTERMITTENT PROBLEMS

REPLACE ECM

Click hereEngine / Hybrid System>2NZ-FE ENGINE CONTROL>ECM>REMOVAL