How to clean a spark plug on a grass trimmer and brushcutter
A clean spark plug helps your Husqvarna grass trimmer or brushcutter start more easily, run smoothly and deliver full engine performance.
Over time carbon deposits can build up on the spark plug, reducing ignition performance. Regular inspection and cleaning help keep your engine running efficiently.
Quick answer
Check the spark plug if your product:
- Is difficult to start
- Runs unevenly at idle
- Loses power during use
- Won’t reach full throttle
Cleaning or replacing the spark plug often restores normal engine performance.
Watch: how to clean a spark plug
The video shows the complete cleaning process, from removing the spark plug to reinstalling it correctly.
Safety first:
Before inspecting the spark plug:
- Wear protective gloves
- Turn off the engine
- Disconnect the spark plug
- Allow the engine to cool completely
What you’ll need:
- Wire brush
- Spak plug wrench or combi spanner
- Clean cloth
- Replacement spark plug (if required)
Always use the spark plug type recommended for your model. An incorrect spark plug can damage the engine.
Step-by-step: clean the spark plug
Access the spark plug
Remove the engine cover (if fitted) and disconnect the spark plug cap.
Remove the spark plug
Use a spark plug wrench or combi spanner.
Turn the spark plug anticlockwise until it can be removed.
Inspect the spark plug
Check for:
- Carbon deposits
- Cracks in the ceramic insulator
- Burnt or worn electrode
- Corrosion
If the spark plug is damaged, replace it instead of cleaning it.
Clean the spark plug
Use a wire brush to remove carbon deposits from the electrode and contact surfaces.
Only reinstall the spark plug if it is clean and undamaged.
Reinstall the spark plug
Thread the spark plug in by hand first.
Tighten it securely using the correct tool, but do not overtighten.
Test the product
Start the grass trimmer or brushcutter and check that it:
- Starts easily
- Idles smoothly
- Accelerates normally
- Maintains power while cutting
When should you replace the spark plug
Replace the spark plug if:
- The ceramic insulator is cracked
- The electrode is badly worn
- Heavy carbon deposits cannot be removed
- Cleaning does not improve performance
Common mistakes to avoid
- Removing the spark plug without cleaning around it first
- Overtightening the spark plug
- Using the wrong spark plug type
- Reinstalling a damaged spark plug
When should you inspect the spark plug?
Inspect the spark plug:
- During routine maintenance
- If the engine becomes difficult to start
- If engine power decreases
- If the engine runs unevenly
A spark plug inspection is one of the quickest ways to identify ignition-related problems.