P0037, P0038, P0057, P0058, P0141, P0161, P102D, P105D

DTC Code	DTC Name
P0037	Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
P0038	Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 2)
P0057	Oxygen Sensor Heater Control Circuit Low (Bank 2 Sensor 2)
P0058	Oxygen Sensor Heater Control Circuit High (Bank 2 Sensor 2)
P0141	Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
P0161	Oxygen Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
P102D	O2 Sensor Heater Circuit Performance Bank 1 Sensor 2 Stuck ON
P105D	O2 Sensor Heater Circuit Performance Bank 2 Sensor 2 Stuck ON

DESCRIPTION

A three-way catalytic converter is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) into less harmful substances. To allow the three-way catalytic converter to function effectively, it is necessary to keep the air fuel ratio of the engine near the stoichiometric air fuel ratio. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a heated oxygen sensor is used.

The heated oxygen sensor is located behind the three-way catalytic converter, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).

When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas becomes rich. The heated oxygen sensor informs the ECM that the post-three-way catalytic converter air fuel ratio is lean (low voltage, i.e. less than 0.45 V).

Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas becomes lean. The heated oxygen sensor informs the ECM that the post-three-way catalytic converter air fuel ratio is rich (high voltage, i.e. more than 0.45 V). The heated oxygen sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level.

The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air fuel ratio after the three-way catalytic converter is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.

Tech Tips

When any of these DTCs are set, the ECM enters fail-safe mode. The ECM turns off the heated oxygen 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 heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.

DTC No.	DTC Detection Condition	Trouble Area
P0037 P0057	Heated oxygen sensor heater (bank 1, 2 sensor 2) current is less than 0.3 A (1 trip detection logic)	Open in heated oxygen sensor heater (bank 1, 2 sensor 2) circuit Heated oxygen sensor (bank 1, 2 sensor 2) ECM
P0038 P0058	Heated oxygen sensor heater (bank 1, 2 sensor 2) current is exceeds the specified value (1 trip detection logic)	Short in heated oxygen sensor heater (bank 1, 2 sensor 2) circuit Heated oxygen sensor (bank 1, 2 sensor 2) ECM
P0141 P0161	Cumulative heater resistance correction value exceeds the acceptable threshold (2 trip detection logic)	Open or short in heated oxygen sensor heater (bank 1, 2 sensor 2) Heated oxygen sensor (bank 1, 2 sensor 2) ECM
P102D P105D	The heater current is higher than the specified value while the heater is not operating (1 trip detection logic).	ECM

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 gas. If the zirconia element is at the appropriate temperature, and the difference between the oxygen concentrations surrounding the inside and outside surfaces of the sensor is large, the zirconia element generates voltage signals. In order to increase the oxygen concentration detecting capacity of the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor.

Heated oxygen sensor heater range check (P0037, P0038, P0057, P0058, P102D and P105D):

The ECM monitors the current applied to the heated oxygen sensor heater to check the heater for malfunctions. If the heater current is outside the normal range, the signal transmitted by the heated oxygen sensor becomes inaccurate. When the current in the heated oxygen sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor and stores a DTC.

Heated oxygen sensor heater performance (P0141 and P0161):

After the accumulated heater on time exceeds 100 seconds, the ECM calculates the heater resistance using the battery voltage and the current applied to the heater. If the resistance is above the threshold value, the ECM will determine that there is a malfunction in the heated oxygen sensor heater and set DTC P0141 or P0161.

MONITOR STRATEGY

Required sensors/Components

Heated oxygen sensor heater

Frequency of operation

Continuous: P0037, P0038, P0057, P0058 P102D and P105D

Once per driving cycle: P0141 and P0161

TYPICAL ENABLING CONDITIONS

P0037 and P0057 (Case 1)
Time after heater ON	10 seconds or more

P0037 and P0057 (Case 2)
Time after heater ON	10 seconds or more

P0038 and P0058
Time after heater ON	10 seconds or more

P0141 and P0161 (Case 1)
Battery voltage	10.5 V or higher
Time after fuel cut ON to OFF	30 seconds or more
Accumulated heater ON time	100 seconds or more

P0141 and P0161 (Case 2)
Duration that rear heated oxygen sensor impedance is less than 15 kΩ	2 seconds or more

P102D and P105D
Time after heater ON	10 seconds or more

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 at least 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: P0037, P0038, P0057, P0058, P0141, P0161, P102D or P105D.

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 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 P0136 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" [O2 Heater B1S2, O2 Heater B2S2, O2 Heater Curr Val B1S2 and O2 Heater Curr Val B2S2] Click here.
When the values for the Data List items O2 Heater Curr Val B1S2 and O2 Heater Curr Val B2S2 are not 0 A, the heaters are on.
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 heated oxygen 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 HEATED OXYGEN SENSOR (HEATER RESISTANCE)
1. Inspect the heated oxygen sensor Click here.
NG
REPLACE HEATED OXYGEN SENSOR Click here

OK

CHECK TERMINAL VOLTAGE (+B OF HEATED OXYGEN SENSOR)

Text in Illustration
*1	Bank 1
*2	Bank 2 (for 2WD)
*3	Bank 2 (for AWD)
*a	Front view of wire harness connector (to Heated Oxygen Sensor)

Disconnect the heated oxygen sensor connector.

Turn the engine switch on (IG).

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

Standard Voltage (for 2WD)

Tester Connection	Switch Condition	Specified Condition
N71-2 (+B) - Body ground	Engine switch on (IG)	11 to 14 V
N47-2 (+B) - Body ground	Engine switch on (IG)	11 to 14 V

Standard Voltage (for AWD)

Tester Connection	Switch Condition	Specified Condition
N71-2 (+B) - Body ground	Engine switch on (IG)	11 to 14 V
U3-2 (+B) - Body ground	Engine switch on (IG)	11 to 14 V

Reconnect the heated oxygen sensor connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (HEATED OXYGEN SENSOR - NO. 1 INTEGRATION RELAY)

OK

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 (for 2WD) (Check for Open)

Tester Connection	Condition	Specified Condition
N71-1 (HT1B) - A21-4 (HT1B)	Always	Below 1 Ω
N47-1 (HT2B) - A21-3 (HT2B)	Always	Below 1 Ω

Standard Resistance (for 2WD) (Check for Short)

Tester Connection	Condition	Specified Condition
N71-1 (HT1B) or A21-4 (HT1B) - Body ground	Always	10 kΩ or higher
N47-1 (HT2B) or A21-3 (HT2B) - Body ground	Always	10 kΩ or higher

Standard Resistance (for AWD) (Check for Open)

Tester Connection	Condition	Specified Condition
N71-1 (HT1B) - A21-4 (HT1B)	Always	Below 1 Ω
U3-1 (HT2B) - A21-3 (HT2B)	Always	Below 1 Ω

Standard Resistance (for AWD) (Check for Short)

Tester Connection	Condition	Specified Condition
N71-1 (HT1B) or A21-4 (HT1B) - Body ground	Always	10 kΩ or higher
U3-1 (HT2B) or A21-3 (HT2B) - Body ground	Always	10 kΩ or higher

Reconnect the heated oxygen sensor connector.
Reconnect the ECM connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (HEATED OXYGEN SENSOR - ECM)

OK

CHECK WHETHER DTC OUTPUT RECURS

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 P0037, P0038, P0057, P0058, P0141, P0161, P103D or P105D is output	B

B

REPLACE ECM Click here

A

CHECK FOR INTERMITTENT PROBLEMS Click here

SFI SYSTEM, Diagnostic DTC:P0037, P0038, P0057, P0058, P0141, P0161, P102D, P105D