Catalytic Converter (diesel engine models).
The exhaust system is specially designed to produce acoustic effects similar to the exhaust sound reproduced by real racing vehicles.
As a result, during acceleration in low gears the interior noise level exceeds the limit established by GOST 51616.
At steady driving speeds, the interior noise level of the vehicle complies with GOST 51616. External vehicle noise complies with UN ECE Regulation No. 51 02.
The three-way catalyst contains precious metals that are used as catalysts and do not take part in the chemical reactions themselves. The catalytic converter of your vehicle reduces emissions of all three main harmful components of exhaust gas: hydrocarbons HC, carbon monoxide CO and nitrogen oxides NOx, as well as particulate matter.
When the converter has reached the end of its service life, install a new catalytic converter manufactured by Honda (or a fully equivalent part) on the vehicle.

Use only the fuel recommended in this manual (see page 299).

Test yourself
A quick Honda Civic quiz: every answer comes with an explanation and a link to the manual page.