P0031, P0032, P0051, P0052, P101D, P103D

DTC Code	DTC Name
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)
P0051	Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 2 Sensor 1)
P0052	Oxygen (A/F) Sensor Heater Control Circuit High (Bank 2 Sensor 1)
P101D	A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON
P103D	A/F Sensor Heater Circuit Performance Bank 2 Sensor 1 Stuck ON

DESCRIPTION

Refer to DTC P2195 Click here.

Tech Tips

When any of these DTCs are set, 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 engine switch is turned off.
The ECM provides 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.

DTC No.	DTC Detection Condition	Trouble Area
P0031 P0051	Air fuel ratio sensor heater (bank 1, 2 sensor 1) current less than 0.8 A, even when the air fuel ratio sensor heater duty cycle is 10% or more (1 trip detection logic)	Open in air fuel ratio sensor heater (bank 1, 2 sensor 1) circuit Air fuel ratio sensor (bank 1, 2 sensor 1) A/F relay ECM
P0032 P0052	Air fuel ratio sensor heater current reaches the high limit (Hybrid IC high current limiter monitor input "Fail") (1 trip detection logic)	Short in air fuel ratio sensor heater (bank 1, 2 sensor 1) circuit Air fuel ratio sensor (bank 1, 2 sensor 1) A/F relay ECM
P101D P103D	The heater current is higher than the specified value while the heater is not operating (1 trip detection logic).	Open or short in air fuel ratio sensor heater (bank 1, 2 sensor 1) circuit ECM

DTC No.

DTC Detection Condition

Trouble Area

P0031

P0051

Air fuel ratio sensor heater (bank 1, 2 sensor 1) current less than 0.8 A, even when the air fuel ratio sensor heater duty cycle is 10% or more

(1 trip detection logic)

Open in air fuel ratio sensor heater (bank 1, 2 sensor 1) circuit
Air fuel ratio sensor (bank 1, 2 sensor 1)
A/F relay
ECM

P0032

P0052

Air fuel ratio sensor heater current reaches the high limit

(Hybrid IC high current limiter monitor input "Fail") (1 trip detection logic)

Short in air fuel ratio sensor heater (bank 1, 2 sensor 1) circuit
Air fuel ratio sensor (bank 1, 2 sensor 1)
A/F relay
ECM

P101D

P103D

The heater current is higher than the specified value while the heater is not operating (1 trip detection logic).

Open or short in air fuel ratio sensor heater (bank 1, 2 sensor 1) circuit
ECM

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 will be inaccurate, as a result, the ECM will be unable to regulate 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 sets a DTC.

MONITOR STRATEGY

Required sensors/Components	Air fuel ratio sensor heater
Frequency of operation	Continuous

TYPICAL ENABLING CONDITIONS

P0031 and P0051
Air fuel ratio sensor heater duty-cycle	10% or more

P0032 and P0052
Air fuel ratio sensor heater duty-cycle	More than 0%

P101D and P103D
Air fuel ratio sensor heater duty-cycle	10 to 60%
Air fuel ratio sensor heater ON current	0.8 A or higher

CONFIRMATION DRIVING PATTERN

Connect the GTS to the DLC3.
Turn the engine switch on (IG) and turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Click here.
Turn the engine switch off and wait for 30 seconds.
Turn the engine switch on (IG) 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].
Read Pending DTCs.
Tech Tips
- If a pending DTC is not output, perform the following procedure.
- If a pending DTC is output, the system is malfunctioning.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0031, P0032, P0051, P0052, P101D or P103D.

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's memory limit

Tech Tips

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

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Note

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

Tech Tips

Refer to "Data List / Active Test" [A/F Heater Duty #1 and A/F Heater Duty #2] Click here.
Bank 1 refers to the bank that includes the No. 1 cylinder*.

*: The No. 1 cylinder is the cylinder which is farthest from the transmission.
Bank 2 refers to the bank that does not include the No. 1 cylinder.
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 here. If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

PROCEDURE

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
1. Inspect the air fuel ratio sensor Click here.
  
  Tech Tips
  
  Perform "Inspection After Repair" after replacing the air fuel ratio sensor Click here.
NG
REPLACE AIR FUEL RATIO SENSOR Click here

OK

CHECK TERMINAL VOLTAGE (+B OF AIR FUEL RATIO SENSOR)

Text in Illustration
*1	Bank 1
*2	Bank 2
*a	Front view of wire harness connector (to Air Fuel Ratio Sensor)

Disconnect the air fuel ratio sensor connector.

Turn the engine switch on (IG).

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

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
F62-2 (+B) - Body ground	Engine switch on (IG)	11 to 14 V
F46-2 (+B) - Body ground	Engine switch on (IG)	11 to 14 V

Reconnect the air fuel ratio sensor connector.

NG

INSPECT NO. 1 INTEGRATION RELAY (A/F) Click here

OK

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 (Check for Open)

Tester Connection	Condition	Specified Condition
F62-1 (HA1A) - F4-5 (HA1A)	Always	Below 1 Ω
F46-1 (HA2A) - F4-6 (HA2A)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
F62-1 (HA1A) or F4-5 (HA1A) - Body ground	Always	10 kΩ or higher
F46-1 (HA2A) or F4-6 (HA2A) - Body ground	Always	10 kΩ or higher

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

NG

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

OK

CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032, P0051, P0052, P101D OR P103D)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs Click here.
Start the engine.
Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

Read the output pending DTCs using the GTS.

Result

Result	Proceed to
Pending DTC is not output	A
Pending DTC P0031, P0032, P0051, P0052, P101D or P103D is output	B

B

REPLACE ECM Click here

A

CHECK FOR INTERMITTENT PROBLEMS Click here

INSPECT NO. 1 INTEGRATION RELAY (A/F)
1. Inspect the No. 1 integration relay (A/F) Click here.
NG
REPLACE NO. 1 INTEGRATION RELAY

OK

CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - NO. 1 INTEGRATION RELAY)

Disconnect the air fuel ratio sensor connector.
Remove the No. 1 integration relay from the No. 2 engine room relay block.

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

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
F62-2 (+B) - 2F-4	Always	Below 1 Ω
F46-2 (+B) - 2F-4	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
F62-2 (+B) or 2F-4 - Body ground	Always	10 kΩ or higher
F46-2 (+B) or 2F-4 - Body ground	Always	10 kΩ or higher

Reinstall the No. 1 integration relay.
Reconnect the air fuel ratio sensor connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - NO. 1 INTEGRATION RELAY)

OK

CHECK TERMINAL VOLTAGE (NO. 1 INTEGRATION RELAY)

Text in Illustration

*a
Front view of wire harness connector

(to No. 1 Integration Relay)

Remove the No. 1 integration relay from the No. 2 engine room relay block.

Text in Illustration
*a	Front view of wire harness connector (to No. 1 Integration Relay)

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

Standard Voltage

Tester Connection	Condition	Specified Condition
2D-1 - Body ground	Always	11 to 14 V

Reinstall the No. 1 integration relay.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - NO. 1 INTEGRATION RELAY)

OK

CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - BODY GROUND)

Remove the No. 1 integration relay from the No. 2 engine room relay block.

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

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
2F-1 - Body ground	Always	Below 1 Ω

Reinstall the No. 1 integration relay.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 1 INTEGRATION RELAY - BODY GROUND)

OK

CHECK ECM POWER SOURCE CIRCUIT Click here

SFI SYSTEM, Diagnostic DTC:P0031, P0032, P0051, P0052, P101D, P103D