0458-838-8601-A
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21 Troubleshooting Guide
21.2 Replacing the Air Filter
Dirty air filters reduce engine power, increase fuel 
consumption and make starting more difficult.
If there is a noticeable loss of engine power:
► Shut off the engine, @ 12.1.
► Allow the trimmer / brushcutter to cool down.
► Turn the choke lever to  position.
► Loosen the screws (1).
► Remove the air filter cover (2).
► Clean the area around the air filter with a damp cloth or a 
soft brush.
► Remove the air filter element (3).
► Fit the new filter in the filter housing.
► Fit the filter cover.
► Insert the screws (1) and tighten them.
21.3 Cleaning the Spark Plug
WARNING
To reduce the risk of fire and burn injury, use only spark 
plugs authorized by STIHL. Always press the spark plug 
boot snugly onto the spark plug terminal.
WARNING
Do not use a spark plug with a detachable SAE adapter 
terminal (1). Arcing may occur that could ignite combustible 
fumes and cause a fire. This can result in serious injuries or 
damage to property. Only use resistor type spark plugs with 
solid, non-threaded terminals (2).
Using the wrong fuel mix (too much engine oil in the 
gasoline), a dirty air filter, and unfavorable running 
conditions (running for extended periods at partial throttle) 
can affect the condition of the spark plug and cause deposits 
to form on the insulator nose, degrading performance.
To clean the spark plug:
► Shut off the engine, @ 12.1.
► Allow the trimmer / brushcutter to cool down.
► Turn the screw (1) counterclockwise.
► Lift the cap (2) and push it backwards.
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