2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0037,P0038,P0057,P0058,P0141,P0161; Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2); 2007 MY LX470 [08/2006

Last Modified: 7-3-2017	6.8:8.0.40	Doc ID: RM000000PFA02AX
Model Year Start: 2007	Model: LX470	Prod Date Range: [08/2006 - ]
Title: 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0037,P0038,P0057,P0058,P0141,P0161; Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2); 2007 MY LX470 [08/2006 - ]

DTC

P0037

Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)

DTC

P0038

Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 2)

DTC

P0057

Oxygen Sensor Heater Control Circuit Low (Bank 2 Sensor 2)

DTC

P0058

Oxygen Sensor Heater Control Circuit High (Bank 2 Sensor 2)

DTC

P0141

Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

DTC

P0161

Oxygen Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)

DESCRIPTION

Refer to DTC P0136 .

HINT:

Sensor 2 refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far from the engine assembly.
When any of these DTCs are set, the ECM enters fail-safe mode. The ECM turns off the Heated Oxygen (HO2) 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 HO2 sensor heater circuit uses a relay on the +B side of the circuit.

DTC No.

DTC Detection Condition

Trouble Area

P0037

P0057

Heated Oxygen (HO2) sensor heater current less than 0.3 A (1 trip detection logic)

Open in Heated Oxygen (HO2) sensor heater circuit
Heated Oxygen (HO2) sensor heater
EFI Relay
ECM

P0038

P0058

Heated Oxygen (HO2) sensor heater current more than 2.0 A (1 trip detection logic)

Short in HO2 sensor heater circuit
HO2 sensor heater
EFI Relay
ECM

P0141

P0161

Cumulative heater resistance correction value exceeds threshold (2 trip detection logic)

Open or short in HO2 sensor heater circuit
HO2 sensor heater
EFI relay
ECM

HINT:

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

MONITOR DESCRIPTION

The sensing portion of the Heated Oxygen (HO2) 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 concentration 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 and P0058):

The ECM monitors the current applied to the O2 sensor heater to check the heater for malfunctions. If the current is below the threshold value, the ECM determines that there is an open circuit in the heater. If the current is above the threshold value, the ECM determines that there is a short circuit in the heater.

The ECM constantly monitors the current applied to the heater. If the ECM detects an open or short circuit, the ECM turns the MIL on and sets a DTC.

If a malfunction is detected, the ECM cuts off the current applied to the heater.

Example:

The ECM sets DTC P0038 or P0058 when the current in the HO2 sensor heater is more than 2 A.

Conversely, when the heater current is less than 0.3 A, DTC P0037 or P0057 is set.

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 determines that there is a malfunction in the HO2 sensor heater and sets DTC P0141 or P0161.

MONITOR STRATEGY

Related DTCs	P0037: Heated oxygen sensor heater (bank 1) range check (low current) P0038: Heated oxygen sensor heater (bank 1) range check (high current) P0057: Heated oxygen sensor heater (bank 2) range check (low current) P0058: Heated oxygen sensor heater (bank 2) range check (high current) P0141: Heated oxygen sensor heater performance (bank 1) P0161: Heated oxygen sensor heater performance (bank 2)
Required sensors / components	Heated oxygen sensor heater (bank 1 and 2)
Required sensors / components	Vehicle speed sensor
Frequency of operation	Continuous: P0037, P0038, P0057 and P0058 Once per driving cycle: P0141 and P0161
Duration	1 second: P0037, P0038, P0057 and P0058 10 seconds: P0141 and P0161
MIL operation	Immediate: P0037, P0038, P0057 and P0058 2 driving cycle: P0141 and P0161
Sequence of operation	None

TYPICAL ENABLING CONDITIONS

Monitor will run whenever these DTCs are not present

None

P0037 and P0057 (Low current):

1. When all conditions below are met	-
Battery voltage	10.5 V or more to less than 20 V
Learned heater current during heater OFF	Completed
Active heater OFF control	Not operating
Active heater ON control	Not operating
Duration of following conditions are met	0.5 seconds or more
- Heater OFF time	Less than 0.1 seconds
- Heater current	Less than 0.3 A
2. Heater OFF time	1 second or more
3. When all conditions below are met	-
Learned heater OFF current operation	Completed
Active heater OFF control	Not operating
Active heater ON control	Not operating
Heater OFF time	Less than 0.1 seconds

P0038 and P0058 (High current):

When one of following conditions is met:	Condition (a), (b) or (c)
(a) When all conditions below are met:	-
Battery voltage	10.5 V or more
Engine	Running
Starter	OFF
Catalyst monitoring active A/F control	Not operating
Active heater OFF control	Not operating
Active heater ON control	Not operating
(b) When all conditions below are met:	-
Battery voltage	10.5 V or more to less than 20 V
Learned heater current during heater OFF	Completed
Active heater OFF control	Not operating
Active heater ON control	Not operating
Heater OFF time	Less than 0.1 seconds
Heater current	2 A or more
(c) Heater OFF time	1 second or more

P0141 and P0161

Battery voltage	10.5 V or more
Fuel cut	OFF
Time after fuel cut ON to OFF	30 seconds or more
Accumulated heater ON time	100 seconds or more
Learned heater current during heater OFF	Completed

TYPICAL MALFUNCTION THRESHOLDS

P0037 and P0057 (Low current):

Heater current - learned heater OFF current

Less than 0.3 A

P0038 and P0058 (High current):

When either condition below is met	-
Learned heater OFF current	More than 2 A
Heater current - Learned heater OFF current	2 A or more

P0141 and P0161 (Performance):

Heater resistance

Varies with sensor element temperature (example: 23 Ω or more)

COMPONENT OPERATING RANGE

Heated Oxygen (HO2) sensor heater current

0.4 to 1 A (when engine idles, HO2 sensor warmed up and battery voltage 11 to 14 V)

MONITOR RESULT

Detailed information on Checking Monitor Status .

The test value and test limit information are in the following table. Check the monitor result and test values after performing the monitor drive pattern (refer to "Confirmation Monitor").

Monitor Identification Date (MID) is assigned to each emission-related component.
Test Identification Date (TID) is assigned to each emission-related component.
Scaling is used to calculate the test value indicated on generic OBD II scan tools.

Heated oxygen sensor heater (Bank 1 sensor 2):

MID	TID	Scaling	Description of Test Value	Minimum Test Limit	Maximum Test Limit
$42	$90	Multiply by 0.001 (A)	Maximum sensor heater current	Minimum test limit	Maximum test limit

Heated oxygen sensor heater (Bank 2 sensor 2):

MID	TID	Scaling	Description of Test Value	Minimum Test Limit	Maximum Test Limit
$46	$90	Multiply by 0.001 (A)	Maximum sensor heater current	Minimum test limit	Maximum test limit

WIRING DIAGRAM

Refer to DTC P0136 .

INSPECTION PROCEDURE

HINT:

If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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.

PROCEDURE

1.	INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

(a) Disconnect the H8 or H17 Heated Oxygen (HO2) sensor connector.

(b) Measure the resistance of the HO2 sensor connector.

Standard resistance (Bank 1, 2 sensor 2):

Tester Connection	Specified Condition
HT (1) - +B (2)	11 to 16 Ω at 20°C (68°F)
HT (1) - E1 (4)	10 kΩ or higher

REPLACE HEATED OXYGEN SENSOR

2.	INSPECT EFI RELAY (Marking: EFI OR ECD)

(a) Remove the EFI relay from the engine room relay block.

(b) Measure the resistance of the EFI relay.

Standard resistance:

Terminal Connection

Specified Condition

1 - 3

10 kΩ or higher

1 - 3

Below 1 Ω

(when battery voltage applied to terminals 2 and 4)

REPLACE EFI RELAY

3.	INSPECT ECM (HT1B OR HT2B VOLTAGE)

(a) Turn the ignition switch ON.

(b) Measure the voltage of the E6, E7 and E8 ECM connectors.

Standard voltage:

Terminal Connection	Specified Condition
E8-1 (HT1B) - E6-1 (E1)	9 to 14 V
E7-5 (HT2B) - E6-1 (E1)	9 to 14 V

HINT:

The HT1B means the heated oxygen sensor bank 1 sensor 2.
The HT2B means the heated oxygen sensor bank 2 sensor 2.

REPLACE ECM

4.	CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - EFI RELAY)

(a) Check harness and connector .

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

(a) Check harness and connector .

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM