Spark plug · NGK
Equivalents for the NGK spark plug 7421
Meet the NGK 7421 spark plug. All its 49 replacement references: compatible and interchangeable equivalents — NGK, Bosch, Champion, Denso…
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What can replace a NGK 7421 spark plug?
The NGK 7421 is interchangeable with: NGK BMR4A, Bosch WSR 8 E, Champion RCJ7, NGK BMR6A, Bosch WSR 9 EC, Champion RCJ8. 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.