Spark plug · NGK
Equivalents for the NGK spark plug 4421
The NGK 4421 spark plug. All its 47 replacement references: compatible and interchangeable equivalents — NGK, Bosch, Champion, Denso…
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47 equivalents compatible with the NGK 4421 spark plug
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What can replace a NGK 4421 spark plug?
The NGK 4421 is interchangeable with: NGK BKR4E, Bosch FR 8 DC, Champion RC12YC, NGK BKR5E, NGK BCPR5E, NGK BKR5EZ. These spark plugs share the same mounting (thread, seat) and heat range.
Cross-references and specifications are provided for guidance only. The wrench size can vary by brand, and some data is inferred from the plug code or an equivalent reference. Always check the vehicle manufacturer's recommendation before buying and fitting.