Catalytic converter

Clean and maintenance-free

STIHL was the first manufacturer to develop a catalytic converter for chainsaws, back in 1988. This minimizes the unburned components of the exhaust and cuts harmful hydrocarbon emissions by up to 80%. The catalytic converter is maintenance-free and does not affect machine operation in any position. STIHL machines with a catalytic converter are indicated by the letter "D" in the model designation.

This is how it works
The catalytic converter reduces the pollutant components by means of a chemical reaction called afterburning. Afterburning is triggered by a special precious metal coating. Cold air is mixed in to cool the exhaust gases.

Afterburning
Although extreme temperatures up to 1,000℃ can occur during exhaust afterburning, a special twin-walled muffler housing ensures that the engine's power and thermal balance are not impaired.