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Brand

NGK

The reference is the specification

Why the code does the work

A spark plug is bought by its reference and by nothing else. BR8HSA, B7HS, CR6HSA encode the thread, the reach, the construction, whether a resistor is fitted, and the heat range.

Two elements are worth naming because they are the ones people get wrong.

R denotes a resistor plug, which suppresses the radio interference an ignition generates. An engine whose manual specifies one wants one.

The digit is the heat range — how fast the plug sheds heat from its tip. Higher is colder. Too hot and it can pre-ignite; too cold and it fouls at low load.

What the listings publish beyond the code

Very little, and it varies. One gives cold-rolled threads with a corrosion-resistant coating and smooth running at low and high speed. One gives three bullets, of which two are the brand name and the reference already in the title.

What none of them gives

Thread size, reach and gap. All three sit in the maker’s own catalogue against the reference. On this shelf, a rival brand publishes M10 × 12.7 mm for its own plug — which is what makes the difference between the B and C series legible at all.

The whole of the NGK range covered here, a page apiece

  • NGK B7HS spark plug in its Yellow Box

    NGK B7HS

    A single NGK Yellow Box standard spark plug, reference B7HS, with cold-rolled corrosion-resistant threads stated for heat dissipation — no resistor in the code.

    Reference
    B7HS (from the title) — no R in the code, and the digit is the heat range
    Range
    Yellow Box, NGK’s standard range following original equipment (maker’s bullet)
    Threads
    Cold-rolled with a corrosion-resistant coating, stated to dissipate heat well (maker’s bullet)
    Operation
    Stated to run smoothly at low and high engine speeds (maker’s bullet)
    Maker’s instruction
    Follow the fitting instructions (maker’s bullet)
    Quantity
    1 plug (maker’s bullet)
    Amazon reference
    DE B0000AXR66 · US B006B7FQIM · GB B006B7FQIM · FR B006B7FQIM · IT B0000AXR66 · ES B006B7FQIM
    EAN
    0087295151105
    • Publishes the thread treatment, which is what stops a plug seizing in an alloy head
    • The clearest contrast in this family: same maker, no resistor, one heat range apart
    • Not a resistor plug — that is a specification, not a saving

    Best for: A machine whose manual names B7HS — and not a substitute for one that names BR8HSA.

    ≈ €3
    Check price on Amazon
  • NGK BR8HSA spark plug in its Yellow Box

    NGK BR8HSA

    A single NGK Yellow Box standard spark plug, reference BR8HSA, published as original-equipment quality with vehicle-specific fitment.

    Reference
    BR8HSA (from the title) — in NGK’s code, R denotes a resistor type and the digit is the heat range
    Range
    Yellow Box, NGK’s standard range (maker’s bullet)
    Fitment
    Vehicle-specific (maker’s bullet)
    Quality
    Stated original-equipment quality (maker’s bullet)
    Quantity
    1 plug (from the title)
    Thread size and reach
    Not published in this listing.
    Amazon reference
    DE B000CSGXDI · US B005Z09IJY · GB B004NMN0MG · FR B005Z09IJY · IT B005Z09IJY · ES B005Z09IJY
    EAN
    0087295155394
    • A named reference from a maker whose code system is documented and cross-referenced everywhere
    • Standard-range plug, which is what most manuals actually specify
    • Four bullets, none of which carries a dimension

    Best for: A machine whose manual names BR8HSA, or a cross-reference that arrives at it.

    ≈ €5
    Check price on Amazon
  • NGK CR6HSA spark plug in its Yellow Box

    NGK CR6HSA

    A single NGK spark plug, reference CR6HSA, whose listing consists of three bullets: original-equipment quality, the brand name, and the reference.

    Reference
    CR6HSA (from the title)
    Code
    C series rather than B; R denotes a resistor; 6 is the heat range
    Quality
    Stated original-equipment quality (maker’s bullet)
    Listing bullets
    Three: "original-equipment quality", "NGK", "CR6HSA".
    Thread size
    Not published in this listing — the Vnuipofa plug in this family publishes M10 for its own C-series reference.
    Gap
    Not published in this listing.
    Amazon reference
    DE B000CSIRHI · US B000CSIRHI · GB B000CSIRHI · FR B0025QX6IU · IT B0077PXDZK · ES B0025QX6IU
    EAN
    0087295129838
    • Published on all six marketplaces at a low price
    • A reference that cross-references cleanly against any manual
    • Three bullets, one of which is the brand name and one of which is the reference already in the title

    Best for: A small-capacity machine whose manual names CR6HSA.

    ≈ $7 / £7 / €5
    Check price on Amazon

Nothing written into the text below is a current price. Where an amount appears in a sentence, it is the reading taken on the day that sentence was written; what a shop is asking at this moment loads beside the product itself, and that is the figure to go by.