Lexus ES300 (2002 year). Manual - part 359

A52607

05-56

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

209

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

4

CHECK HARNESS AND CONNECTOR(ECM - A/F SENSOR)

NG

REPAIR OR REPLACE HARNESS AND
CONNECTOR

OK

5

INSPECT AIR FUEL RATIO SENSOR(CHECK HEATER RESISTANCE)

(a)

Disconnect the air fuel ratio sensor.

(b)

Measure resistance between the terminals HT and +B of
the air fuel ratio sensor.
Resistance: 2.16 - 2.88 

Ω

 (20



C)

NG

REPLACE AIR FUEL RATIO SENSOR

OK

6

CHECK AIR INDUCTION SYSTEM (See page 

11-1

)

NG

REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK

7

CHECK FUEL PRESSURE (See page 

11-4

)

NG

REPAIR OR REPLACE FUEL SYSTEM

OK

8

INSPECT FUEL INJECTOR ASSY (See page 

11-7

)

NG

REPLACE FUEL INJECTOR ASSY

OK

9

CHECK EXHAUST GAS LEAK

NG

REPAIR OR REPLACE EXHAUST GAS
LEAKAGE POINT

OK

REPLACE AIR FUEL RATIO SENSOR

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-57

210

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

10

PERFORM CONFIRMATION DRIVING PATTERN (See page 

05-52

)

GO

11

READ OUTPUT DTC(DTC P0125 OUTPUT AGAIN)

YES

CHECK AND REPLACE ECM

NO

12

CONFIRM VEHICLE RUNS OUT OF FUEL IN THE PAST

NO

CHECK FOR INTERMITTENT PROBLEMS

YES

DTC P0125 IS CAUSED BY RUNNING OUT OF FUEL

05-58

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

211

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

P0128

THERMOSTAT MALFUNCTION

CIRCUIT DESCRIPTION

If the water temperature becomes 75

°

C (167

°

F) or more, it is abnormal.

If not due to the thermostat malfunction, it is abnormal.

DTC No.

DTC Detecting Condition

Trouble Area

P0128

Condition (a), (b) or (c):

(a) After starting engine at 20

°

C (68

°

F)

(b) After engine is warmed up

(c) THW < 75

°

C (167

°

F)

Thermostat

Cooling system

E.F.I. engine coolant temp. sensor

ECM

INSPECTION PROCEDURE

HINT:
Read freeze frame data using hand-held tester or OBD II scan tool. Because freeze frame records the en-
gine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether
the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich,
etc. at the time of the malfunction.

1

INSPECT THERMOSTAT (See page 

16-12

)

NG

REPLACE THERMOSTAT

OK

2

CHECK OTHER DTC OUTPUT(BESIDES DTC P0128)

YES

GO TO RELEVANT DTC CHART

NO

CHECK AND REPLACE ECM

051M2-06

-

DIAGNOSTICS

SFI SYSTEM (1MZ-FE)

05-59

212

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

P0136

HEATED OXYGEN SENSOR CIRCUIT
MALFUNCTION(BANK1 SENSOR2)

DTC

P0156

HEATED OXYGEN SENSOR CIRCUIT
MALFUNCTION (BANK2 SENSOR2)

CIRCUIT DESCRIPTION

Refer to DTC P0125 on page 

05-52

.

DTC No

DTC Detecting Condition

Trouble Area

P0136
P0156

Condition (a) and (b) continues for 60 secs. or more:

(a) Voltage output of oxygen sensor remains at 0.35 V or more,

or 0.55 V or less, during idling after engine is warmed up

(b) Oxygen sensor output voltage amplitude is less than 0.3 V.

Oxygen sensor

Fuel trim malfunction

HINT:

After confirming DTC P0125, use the hand−held tester to confirm voltage output of the oxygen sensor (bank
1 sensor 2) from the CURRENT DATA.
If voltage output of the oxygen sensor (bank 1 sensor 2) is less than 0.1 V, oxygen sensor (bank 1 sensor
2) circuit may be open or short.

056H6-01