Spark Plug Inspection - L15A1 (IN model) and L15A6

1.Inspect the electrodes and ceramic insulator.

  • Burned or worn electrodes may be caused by:
    • Advanced ignition timing
    • Loose spark plug
    • Plug heat range too hot
    • Insufficient cooling

  • Fouled plug may be caused by:
    • Retarded ignition timing
    • Oil in combustion chamber
    • Incorrect spark plug gap
    • Plug heat range too cold
    • Excessive idling/low speed running
    • Clogged air cleaner element
    • Deteriorated ignition coils


2.Check the electrode gap (A). If the gap is over the standard, adjust the gap with suitable gapping tool.

Electrode Gap 
Standard (New): 1.0-1.1 mm (0.039-0.043 in.) 


3.Replace the plug at the specified interval, or if the center electrode is rounded (A). Use only the spark plugs as listed.

Spark Plugs 
L15A1 engine (IN model): 
NGK: ZFR6K-11 
L15A6 engine: 
NGK: ZFR6J-11 


4.Apply a small quantity of anti-seize compound to the plug threads, and screw the plugs into the cylinder head finger-tight. Then torque them to 18 N·m (1.8 kgf·m, 13 lbf·ft).