Honda FourTrax Rancher TRX420FA5 2019, Owner'S Manual

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Technical Information 239
Emission Control Systems
Source of Exhaust Emissions
The combustion process produces carbon monoxide (CO), oxides of
nitrogen (NOx) and hydrocarbons (HC). Control of hydrocarbons and
oxides of nitrogen is very important because, under certain
conditions, they react to form photochemical smog when subjected
to sunlight. Carbon monoxide does not react in the same way, but it
is toxic.
Honda Motor Co., Ltd. utilizes various systems to reduce carbon
monoxide, oxides of nitrogen and hydrocarbons.
Exhaust Emission Control System
The exhaust emission control system includes a PGM-FI system and
oxygen sensor.
No adjustment to this system should be made although periodic
inspection of the components is recommended.
The exhaust emission control system is separate from the crankcase
emission control system.
Crankcase Emission Control System
The engine is equipped with a closed crankcase system to prevent
discharging crankcase emissions into the atmosphere. Blow-by gas is
returned to the combustion chamber through the air cleaner.
19 TRX420FA5 FA6-31HR7640.book Page 239 Tuesday, May 29, 2018 10:11 AM