2ZR-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) P101D A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON

DESCRIPTION

HINT:: Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.

The air fuel ratio sensor generates a voltage* that corresponds to the actual air fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection time. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is a planar type and is integrated with a heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), current flows to the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are a narrow type. The heat generated by the heater is conducted to the solid electrolyte through alumina, and therefore the sensor activation is accelerated.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.

*: Value changes inside the ECM. Since the air fuel ratio sensor is a current output element, the current is converted into a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

1.615,2.969 0.979,2.49 false 1.823,2.969 2.094,2.667 false 2.927,1.76 3.521,0.729 false 3.052,1.792 3.615,1.427 false 3.208,2.188 3.698,1.781 false 2.854,2.396 3.583,2.198 3.583,2.198 3,2.396 false 3.063,2.469 3.49,2.74 false 0.156,3.271 0.99,3.615 0.833,0.344 10 Exhaust Gas 0.438,2.375 0.979,2.708 0.542,0.333 10 Element 2.115,2.563 2.51,2.865 0.396,0.302 10 Cover 1.125,3.406 1.271,3.604 0.146,0.198 10 A 2.01,3.406 2.156,3.604 0.146,0.198 10 A 3.552,0.646 4.708,1.292 1.156,0.646 10 Solid Electrolyte (Zirconia Element) 3.625,1.313 4.448,1.615 0.823,0.302 10 Alumina 3.719,1.708 4.708,1.99 0.99,0.281 10 Heater 3.604,2.125 5.021,2.469 1.417,0.344 10 Platinum Electrode 3.51,2.646 4.521,2.99 1.01,0.344 10 Atmospheric Air 2.583,3.167 3.75,3.531 1.167,0.365 10 A-A Cross Section 5.677,3.125 6.573,3.469 0.896,0.344 10 Air Fuel Ratio 5.104,0.667 6.979,1.26 1.875,0.594 10 ECM Monitored Air Fuel Ratio Sensor Voltage

HINT:: ·

When any of these DTCs are stored, the ECM enters fail-safe mode. The ECM turns off the air fuel ratio sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned off.

·

Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.

·

The ECM has a pulse width modulated control circuit to adjust the current through the heater. The air fuel ratio sensor heater circuit uses a relay on the +B side of the circuit.

0.083,0.094 2.708,0.354 2.625,0.26 10 Reference (System Diagram of Sensor 1): 0.156,1.125 0.979,1.344 0.823,0.219 10 from Battery 1.094,1.302 1.917,1.521 0.823,0.219 10 EFI-MAIN 1.802,2.333 2.625,2.552 0.823,0.219 10 EFI-MAIN 2.594,1.302 3.417,1.521 0.823,0.219 10 EFI NO. 2 3.385,2.01 4.854,2.271 1.469,0.26 10 Air Fuel Ratio Sensor 3.26,1.552 3.771,1.74 0.51,0.188 10 A1A- 4.438,1.552 4.948,1.74 0.51,0.188 10 A1A+ 4.427,1.031 4.938,1.219 0.51,0.188 10 HA1A 3.365,1.042 3.875,1.229 0.51,0.188 10 +B 3.781,0.854 4.292,1.042 0.51,0.188 10 Heater 3.781,1.302 4.292,1.49 0.51,0.188 10 Sensor 4.948,1.031 5.458,1.219 0.51,0.188 10 HA1A 4.969,1.563 5.479,1.75 0.51,0.188 10 A1A+ 4.979,2.104 5.49,2.292 0.51,0.188 10 A1A- 4.969,2.635 5.479,2.823 0.51,0.188 10 MREL 6.167,1.667 6.656,2.031 0.49,0.365 10 Duty Control 5.729,3.281 6.24,3.469 0.51,0.188 10 ECM

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P0031	Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)	Air fuel ratio sensor heater current is less than 0.8 A, even when the air fuel ratio sensor heater duty cycle is 30% or higher (1 trip detection logic).	· Open in air fuel ratio sensor (sensor 1) heater circuit · Air fuel ratio sensor (sensor 1) · ECM	Comes on	DTC stored
P0032	Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1)	Air fuel ratio sensor heater current reaches the high limit (1 trip detection logic).	· Short in air fuel ratio sensor (sensor 1) heater circuit · Air fuel ratio sensor (sensor 1) · ECM	Comes on	DTC stored
P101D	A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON	The heater current is higher than the specified value while the heater is not operating (1 trip detection logic).	· Short in air fuel ratio sensor (sensor 1) heater circuit · ECM	Comes on	DTC stored

MONITOR DESCRIPTION

The ECM uses information from the air fuel ratio 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 to purify the exhaust gases.

The air fuel ratio 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 air fuel ratio 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 air fuel ratio sensor becomes inaccurate. As a result, the ECM is unable to regulate the air fuel ratio properly.

When the current in the air fuel ratio sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and stores a DTC.

MONITOR STRATEGY

Frequency of Operation

Continuous

TYPICAL ENABLING CONDITIONS

P0031
Heater output duty cycle	30% or higher

P0032
Heater output duty cycle	Higher than 0%

P101D
Heater output duty cycle	Less than 60%

CONFIRMATION DRIVING PATTERN

0.792,1.021 1.438,1.219 0.646,0.198 10 3000 rpm 1.031,1.771 1.5,2.115 0.469,0.344 10 Idling 0.229,2.052 1.396,2.396 1.167,0.344 10 Ignition Switch ON 1.927,2.156 2.333,2.521 0.406,0.365 10 [A] 2.76,1.656 3.167,2.031 0.406,0.375 10 [B] 4.021,0.896 4.333,1.115 0.313,0.219 10 [C] 5.385,1.646 5.833,1.958 0.448,0.313 10 [D] 2.365,2.604 3.844,3.01 1.479,0.406 10 5 minutes or more 4.854,2.604 6.229,2.833 1.375,0.229 10 5 minutes or more 3.896,2.604 4.635,2.844 0.74,0.24 10 1 minute 5.969,3.021 6.323,3.323 0.354,0.302 10 [E]

Connect the GTS to the DLC3.

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

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

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 the pending DTCs.

HINT:: ·

If a pending DTC is output, the system is malfunctioning.

·

If a pending 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, P0032 or P101D.

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

0.531,1.281 1.76,1.479 1.229,0.198 10 false EFI-MAIN 1.427,1.563 2.656,1.76 1.229,0.198 10 false EFI-MAIN 0.542,2.677 1.771,2.875 1.229,0.198 10 false FL MAIN 0.698,3.948 1.927,4.146 1.229,0.198 10 false Battery 1.625,4.073 2.854,4.271 1.229,0.198 10 false *: Shielded 2.583,0.635 3.813,0.833 1.229,0.198 10 false EFI NO. 2 1.271,0.406 1.5,0.563 0.229,0.156 10 false 5 2.073,0.406 2.302,0.563 0.229,0.156 10 false 3 1.302,1.135 1.531,1.292 0.229,0.156 10 false 2 2.063,1.125 2.292,1.281 0.229,0.156 10 false 1 3.76,0.385 3.99,0.542 0.229,0.156 10 false 2 3.75,1.135 3.979,1.292 0.229,0.156 10 false 4 4.906,1.125 5.135,1.281 0.229,0.156 10 false 3 4.917,0.385 5.146,0.542 0.229,0.156 10 false 1 3.938,0.385 4.219,0.573 0.281,0.188 10 false +B 4.469,0.385 4.865,0.573 0.396,0.188 10 false HA1A 3.927,1.083 4.323,1.271 0.396,0.188 10 false A1A- 4.521,1.083 4.917,1.271 0.396,0.188 10 false A1A+ 3.76,1.656 4.156,1.844 0.396,0.188 10 false B17 3.76,1.802 5.208,2 1.448,0.198 10 false Air Fuel Ratio Sensor 5.344,0.979 5.573,1.135 0.229,0.156 10 false * 5.969,0.302 6.365,0.49 0.396,0.188 10 false 27 5.938,1.052 6.333,1.24 0.396,0.188 10 false 100 5.927,2.458 6.323,2.646 0.396,0.188 10 false 132 5.969,3.188 6.365,3.375 0.396,0.188 10 false 46 5.927,0.5 6.323,0.688 0.396,0.188 10 false B64 5.927,1.24 6.323,1.427 0.396,0.188 10 false B64 5.938,2.646 6.333,2.833 0.396,0.188 10 false B64 5.927,3.375 6.323,3.563 0.396,0.188 10 false A40 6.448,4.063 6.938,4.25 0.49,0.188 10 false ECM 6.26,0.51 6.656,0.698 0.396,0.188 10 false HA1A 6.26,1.229 6.656,1.417 0.396,0.188 10 false A1A+ 6.271,2.646 6.667,2.833 0.396,0.188 10 false A1A- 6.26,3.385 6.771,3.573 0.51,0.188 10 false MREL

CAUTION / NOTICE / HINT

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

HINT:: ·

Refer to "Data List / Active Test" [A/F Heater Duty B1S1].

Click hereEngine / Hybrid System>2ZR-FE ENGINE CONTROL>SFI SYSTEM>DATA LIST / ACTIVE TEST

·

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

·

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

·

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 air fuel ratio sensor output voltage (Click hereEngine / Hybrid System>2ZR-FE ENGINE CONTROL>SFI SYSTEM>P0137). If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

PROCEDURE

1.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Inspect the air fuel ratio sensor.

Click hereEngine / Hybrid System>2ZR-FE ENGINE CONTROL>AIR FUEL RATIO SENSOR>INSPECTION

HINT:: Perform "Inspection After Repair" after replacing the air fuel ratio sensor.; Click hereEngine / Hybrid System>2ZR-FE ENGINE CONTROL>SFI SYSTEM>INITIALIZATION

Result:

Proceed to
OK
NG

2.CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR)

REPLACE AIR FUEL RATIO SENSOR

Click hereEngine / Hybrid System>2ZR-FE ENGINE CONTROL>AIR FUEL RATIO SENSOR>REMOVAL

2.CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR)

0.635,1.979 1.125,2.271 0.49,0.292 1.948,2.042 2.542,1.865 true 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 B17

*a	Front view of wire harness connector (to Air Fuel Ratio Sensor)

Disconnect the air fuel ratio 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
B17-2 (+B) - Body ground	Ignition switch ON	11 to 14 V

Result:

Proceed to
OK
NG

3.CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

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

3.CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

Disconnect the air fuel ratio 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
B17-1 (HA1A) - B64-27 (HA1A)	Always	Below 1 Ω
B17-1 (HA1A) or B64-27 (HA1A) - Body ground and other terminals	Always	10 kΩ or higher

Result:

Proceed to
OK
NG

4.CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032 OR P101D)

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032 OR P101D)

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, P0032 or P101D is output	B

CHECK FOR INTERMITTENT PROBLEMS

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

REPLACE ECM

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