Lexus RX300 (MCU15). Service manual - part 426

EC026–03

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EMISSION CONTROL

EMISSION CONTROL SYSTEM

EC–1

LEXUS RX300   (RM785E)

EMISSION CONTROL SYSTEM

PURPOSE

The emission control systems are installed to reduce the amount of CO, HC and NOx exhausted from the
engine ((3) and (4)), to prevent the atmospheric release of blow–by gas–containing HC (1) and evaporated
fuel containing HC being released from the fuel tank (2).
The function of each system is shown in these table.

System

Abbreviation

Function

(1) Positive Crankcase Ventilation

(2) Evaporative Emission Control

(3) Three–Way Catalytic Converter

(4) Electronic Fuel injection*

PCV

EVAP

TWC

EFI

Reduces HC

Reduces evaporated HC

Reduces HC, CO and NOx

Injects a precisely timed, optimum amount of fuel for reduced

exhaust emissions

Remark: * For inspection and repair of the EFI system, refer to the FI section of this manual.

EC027–05

B12168

VSV for EVAP

Vacuum Surge Tank

Charcoal Canister

TWC

PCV Valve

WU–TWC
(for Bank 2)

WU–TWC
(for Bank 1)

A/F Sensor
(Bank 2 Sensor 1)

A/F Sensor
(Bank 1 Sensor 1)

EC–2

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EMISSION CONTROL

PARTS LAYOUT AND SCHEMATIC DRAWING

LEXUS RX300   (RM785E)

PARTS LAYOUT AND SCHEMATIC DRAWING

 LOCATION

EC028–05

B12169

A/F Sensor
(Bank 2 Sensor 1)

Heated Oxygen Sensor
(Bank 1 Sensor 2)

TWC

Fuel Tank

Charcoal
Canister

WU–TWC
(for Bank 2)

Air Cleaner

WU–TWC
(for Bank 1)

VSV for EVAP

A/F Sensor
(Bank 1 Sensor 1)

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EMISSION CONTROL

PARTS LAYOUT AND SCHEMATIC DRAWING

EC–3

LEXUS RX300   (RM785E)

DRAWING

B00640

PCV Valve

EC029–04

P02006

Clean Hose

Cylinder Head Side

P02477

Intake Manifold
Side

P12931

EC–4

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EMISSION CONTROL

POSITIVE CRANKCASE VENTILATION (PCV) 
SYSTEM

LEXUS RX300   (RM785E)

POSITIVE CRANKCASE
VENTILATION (PCV) SYSTEM

INSPECTION

1.

REMOVE PCV VALVE

(a)

Disconnect the PCV hose from the PCV valve.

(b)

Remove the PCV valve.

2.

INSTALL CLEAN HOSE TO PCV VALVE

3.

INSPECT PCV VALVE OPERATION

(a)

Blow air into the cylinder head side, and check that air
passes through easily.

CAUTION:
Do not suck air through the valve.
Petroleum substances inside the valve are harmful.

(b)

Blow air into the intake manifold side, and check that air
passes through with difficulty.

If operation is not as specified, replace the PCV valve.
4.

REMOVE CLEAN HOSE FROM PCV VALVE

5.

REINSTALL PCV VALVE

6.

VISUALLY INSPECT HOSES, CONNECTIONS AND
GASKETS

Check for cracks, leaks or damage.