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Prices may varyThis product ranks #4 of 31 in Spark Plug.Three above it ↓
Last reviewed May 27, 2026
TL;DR NGK is the OE supplier for Subaru EJ255/EJ257 engines; this iridium plug cross-references dealer parts 22401AA670 and 22401AA720, ships pre-gapped to 1.1mm, and is rated 100,000 miles.
Iridium center electrode with platinum-tipped ground and a silver-alloy laser weld (SILFR designation). Heat range 6, M14×1.25 thread, 26.5mm reach, gasket seat, factory gap 1.1mm matching Subaru OEM spec for the EJ255 and EJ257. NGK supplies this plug to Subaru dealer channels as 22401AA670 and 22401AA720, covering WRX, STI, Legacy GT, Outback XT, and Forester XT from 2004 to 2014. Center electrode tip diameter is not disclosed in the product listing. Community reports no heat-range complaints on any listed application; gap is confirmed factory pre-set.
Right pick for a 2004-2014 Subaru EJ255 or EJ257 on a 100,000-mile interval; OEM provenance and dealer-PN cross-reference confirmed. Skip if the engine needs a colder heat range or tighter gap for high-boost operation.
No chemical exposure from the plug itself. Iridium and platinum tips carry small precious-metal mass per plug, partially offset by the long service interval. Steel shell is recyclable as ferrous scrap; the alumina-ceramic insulator goes to landfill.
Marketing copy from NGK, via Amazon. Not editorial.
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