Lexus ES300 (1997 year). Service manual - part 318

P18349

DI–48

–

DIAGNOSTICS

ENGINE

200

1997 LEXUS ES300   (RM511U)

3

Check output voltage of heated oxygen sensor during idling.

PREPARATION:
Warm up the heated oxygen sensor with the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBD II scan tool or LEXUS hand–held tester read the output voltage of the heated oxygen sensor
during idling.
OK:

Heated oxygen sensor output voltage:
Alternates repeatedly between less than 0.4 V and more than 0.55 V (See the following table).

OK

 Perform confirmation driving pattern
(See page 

DI–46

).

NG

Replace heated oxygen sensor.

DI–50

–

DIAGNOSTICS

ENGINE

202

1997 LEXUS ES300   (RM511U)

DTC

P0135

Heated Oxygen Sensor Heater Circuit 
Malfunction (Bank 1 Sensor 1)

DTC

P0141

Heated Oxygen Sensor Heater Circuit 
Malfunction (Bank 1 Sensor 2)

DTC

P0155

Heated Oxygen Sensor Heater 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

P0135

P0141

When the heater operates, heater current exceeds 2 A 

(2 trip detection logic)

Open or short in heater circuit of heated oxygen sensor

H

t d

h

t

P0141

P0155

Heater current of 0.2 A or less when the heater operates

(2 trip detection logic)

Heated oxygen sensor heater

ECM

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.

Sensor 2 refers to the sensor farther away from the engine body.

WIRING DIAGRAM

Refer to  DTC P0125 on page 

DI–43

 for the WIRING DIAGRAM.

DI09L–01

A00220

ON

HTR(+)

HTL(+) HTS(+)

BE6653
S04160

–

DIAGNOSTICS

ENGINE

DI–51

203

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

1

Check voltage between terminals HTR, HTS, HTL of ECM connectors and body
ground.

PREPARATION:
(a)

Remove the glove compartment (See page 

SF–64

).

(b)

Turn ignition switch ON.

CHECK:
Measure voltage between terminals HTR, HTS, HTL of ECM
connectors and body ground.
HINT:

Connect terminal HTR to bank 1 sensor 1.

Connect terminal HTS to bank 1 sensor 2.

Connect terminal HTL to bank 2 sensor 1.

OK:

Voltage:  9 

∼

 14 V

OK

 Check and replace ECM (See page 

IN–27

).

NG

2

Check resistance of heated oxygen sensor heater (See page 

SF–63

).

NG

 Replace heated oxygen sensor.

OK

Check and repair harness or connector between EFI main relay (Marking: EFI), heated oxygen
sensor and ECM (See page 

IN–27

).

DI–52

–

DIAGNOSTICS

ENGINE

204

1997 LEXUS ES300   (RM511U)

DTC

P0136

Heated Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 2)

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

P0136

 Voltage output of the heated oxygen sensor (bank 1 sensor 2)

remains at 0.4 V or more or 0.5 V or less when the vehicle is

driven at 50 km/h (31 mph) or more after the engine is warmed

up 

(2 trip detection logic)

Heated oxygen sensor

HINT:

Bank 1 refers to the bank that includes cylinder No.1. Sensor 2 refers to the sensor farther away from

the engine body.

WIRING DIAGRAM

Refer to DTC P0125 on page 

DI–43

 for the WIRING DIAGRAM.

INSPECTION PROCEDURE

1

Are there any other codes (besides DTC P0136) being output?

YES

 Go to relevant DTC chart.

NO

2

Check for open and short in harness and connector between ECM and heated
oxygen sensor (See page 

IN–27

).

NG

 Repair or replace harness or connector.

OK

DI09M–01