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Lexus ES300 (1997 year). Manual - part 317

S05724

EFI

Relay

EFI

Junction
Connector

B–Y

J28

J29

IK3

FL
MAIN

Battery

Fusible
Link
Block

J28

From Ignition Switch

B–G

W–B

J23
Junction
Connector

B–Y

Heated Oxygen Sensor

B–Y

Heated Oxygen

(Bank 2 Sensor 1)

(Bank 1 Sensor 1)

Sensor

Heated Oxygen Sensor

(Bank 1 Sensor 2)

IK1

L–B

P–B

Y–R

E10

ECM

OXL1

HTL1

OXR1

E03

HTR

OXS

HTS

Engine
Room

J/B

DI–44

–

DIAGNOSTICS

ENGINE

196

1997 LEXUS ES300 (RM511U)

HINT:

After confirming DTC P0125 use the OBD II scan tool or LEXUS hand−held tester to confirm voltage

output of heated oxygen sensor (bank 1, 2 sensor 1) from CURRENT DATA.

If voltage output of heated oxygen sensor (bank 1, 2 sensor 1) is 0 V, heated oxygen sensor (bank 1, 2 sensor
1) circuit may be open or short.

WIRING DIAGRAM

INSPECTION PROCEDURE

Connect OBD II scan tool or LEXUS hand–held tester and read value for
voltage output of heated oxygen sensor (bank 1, 2 sensor 1).

PREPARATION:
(a)

Connect the OBD II scan tool or LEXUS hand–held tester to the DLC3.

(b)

Warm up engine to normal operating temp.

CHECK:
Read voltage output of heated oxygen sensor (bank 1 sensor 1) when engine is suddenly raced.
HINT:Perform quick racing to 4,000 rpm 3 times using accelerator pedal.
OK:

Both heated oxygen sensors

[

(bank 1 sensor 1) (bank 2 sensor 1)

]

output a RICH signal

(0.45 V or more) at least once.

Check and replace ECM (See page

IN–27

–

DIAGNOSTICS

ENGINE

DI–45

197

1997 LEXUS ES300 (RM511U)

Check for open and short in harness and connector between ECM and heated
oxygen sensor (bank 1, 2 sensor 1) (See page

IN–27

Repair or replace harness or connector.

Replace heated oxygen sensor
(bank 1, 2 sensor 1).

FI7130

Vehicle speed

∼

65 km/h

(31

∼

40 mph)

Idling

IG SW OFF

∼

3 min.

1 min.

Time

(1)(2)

(3)

(4)

(5)

DI–46

–

DIAGNOSTICS

ENGINE

198

1997 LEXUS ES300 (RM511U)

DTC

P0130

Heated Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 1)

DTC

P0150

Heated Oxygen Sensor Circuit Malfunction
(Bank 2 Sensor 1)

CIRCUIT DESCRIPTION

Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page

DI–43

DTC No.

DTC Detecting Condition

Trouble Area

P0130

P0150

Voltage output of heated oxygen sensor remains at 0.4 V or

more, or 0.55 V or less, during idling after the engine is

warmed up (2 trip detection logic)

Heated oxygen sensor

Fuel trim malfunction

HINT:

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

cylinder No.1. Sensor 1 refers to the sensor closer to the engine body.

The heated oxygen sensor’s output voltage and the short−term fuel trim value can be read using the
OBD II scan tool or LEXUS hand−held tester.

WIRING DIAGRAM

Refer to DTC P0125 on page

DI–43

for the WIRING DIAGRAM.

CONFIRMATION DRIVING PATTERN

(1) Connect the LEXUS hand–held tester to the DLC3.
(2) Switch the LEXUS hand–held tester from normal mode to check mode (See page

DI–3

(3) Start the engine and warm it up with all accessory switches OFF.
(4) Drive the vehicle at 50

∼

65 km/h (31

∼

40 mph) for 1

∼

3 min. to warm up the heated oxygen sensor.

(5) Let the engine idle for 1 min.

HINT:If a malfunction exists, the MIL will light up during step (5).
NOTICE:If the conditions in this test are not strictly followed, detection of the malfunction will not
be possible .
If you do not have a LEXUS hand–held tester, turn the ignition switch OFF after performing steps (3)
to (5), then perform steps (3) to (5) again.

DI09J–01