Mazda CX-5 Spark Plugs: Intervals, Fitment & Warning Signs

A genuinely important, counter-intuitive warning: repeatedly removing coil boots to "just check" plugs risks a microscopic scratch that modern high-voltage ignition systems can't tolerate — plus a real aftermarket boot fitment trap.

Illustration for editorial purposes

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OEM Part Number: confirm via engine code — aftermarket NGK 1654 / Bosch 0 242 135 529

Accuracy note: Covers the Mazda CX-5 (KE 2012-2017) as listed in the UK aftermarket catalogues. Spark plugs are engine-specific — thread size (M12 vs M14), reach, heat range, electrode type (copper, platinum, iridium) and gap all change between engines in the same car, and the catalogue listings below cover every petrol engine in the generation without always saying which plug fits which. Match the plug to your engine code (on the V5C or the engine cover), fit a full set of the same type, and use the maker's gap and torque. Genuine numbers are shown only where a listing quotes one.

Petrol engines in this generation	2.0 (KE107, KEEFW, KEEAW) and 2.5 (KE5FW, KE5AW, KE103); diesel 2.2 D (KE2FW, KE2AW, KE102) also listed
Spark plugs (aftermarket)	NGK 1654 (iridium, M12x1.25, 14 mm hex); NGK 6283 (iridium, M12x1.25, 14 mm hex); NGK 94124 (iridium, M12x1.25, 14 mm hex); NGK 93936 (iridium, 1.1 mm gap, M12x1.25, 14 mm hex); Denso ZC20HPR11 (iridium centre, platinum earth, M12x1.25; OE P51R-18-110); Denso IXEH22TT (iridium centre, platinum earth, M12x1.25); Champion OE253 (iridium, 1.0 mm gap, M12x1.25, 14 mm hex)
Genuine (OE) numbers quoted	Denso ZC20HPR11 = P51R-18-110
Fitment notes	The SKYACTIV-G 2.0 and 2.5 take an M12x1.25 / 14 mm hex iridium plug with a gap of 1.0 to 1.1 mm; the M14x1.25 nickel plugs (NGK 7060, Ridex 686S0031) are for other engines, and the plugs are not matched to individual KE engine codes. Brisk 1708 quotes a 100,000 km interval.

A Genuinely Important, Counter-Intuitive Warning Worth Knowing — Mazda CX-5 Spark Plugs

This is genuinely worth knowing before repeatedly pulling plugs to "just check" them: every time a coil and boot is removed and reinstalled over a spark plug, there's a genuine risk of causing a microscopic scratch on the plug's porcelain insulator. On modern engines specifically, this risk is considerably higher than it used to be on older cars — leaner fuel mixtures and wider plug gaps mean today's ignition systems require far higher voltage (often 12,000-14,000V, compared with 6,000-10,000V decades ago), meaning a tiny scratch that would once have gone unnoticed can now genuinely cause a misfire, and in turn risk damaging the catalytic converter if left unaddressed. It's genuinely worth avoiding unnecessary plug removal for inspection alone unless there's a specific reason to suspect a fault, rather than pulling them "just to check" as a routine habit.

A genuinely real, documented fitment trap worth knowing about aftermarket ignition boots: one documented case saw aftermarket boots that were noticeably shorter than genuine OEM boots cause genuine misfires that were initially, mistakenly blamed on the new spark plugs themselves — the fault only resolved once the original-length boots were refitted. If you're chasing a misfire that appeared right after fitting aftermarket plugs or boots, it's genuinely worth comparing the physical length against the originals before assuming the plugs themselves are faulty.

It's also worth knowing a genuinely useful diagnostic distinction: finding oil specifically on the threads of a newly fitted spark plug points toward a valve cover gasket or seal leak allowing oil to seep down into the plug well, rather than a fault with the plug or coil itself. If you're seeing this, it's worth having the valve cover gasket inspected rather than continuing to swap plugs and coils, since neither will resolve a leak originating elsewhere.

Mazda CX-5 Spark Plugs: A Cheap Part That Causes Expensive-Feeling Problems

On the Mazda CX-5, there's rarely a clear signal when spark plugs wear out — just a rougher idle, marginally less pep off the line — vague enough to get pinned on other engine issues. Since the part costs so little, it's also one of the easiest things to keep putting off.

Mazda CX-5 Spark Plugs: Watch: Replacing It

🎬 Watch: 2013-2016 Mazda CX-5 Spark Plug Replacement

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KE generation.

Before you buy: plug type and gap specification vary by engine size and generation. Always confirm against your VIN before ordering.

Mazda CX-5 Spark Plugs: What They Do

On the Mazda CX-5, combustion efficiency, fuel economy and smooth running all trace back to spark plug condition, since these are what ignite the compressed fuel-air mixture in each cylinder. Petrol engines depend on them entirely — diesels skip spark plugs altogether, igniting fuel through compression instead.

Mazda CX-5 Spark Plugs: Generations & Spark Plug Count

Diesel variants, where fitted	Not applicable — diesel engines use compression ignition and have no spark plugs at all
Petrol variants (all trims)	4 spark plugs — one per cylinder

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Mazda CX-5 Spark Plugs: Warning Signs, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Spark Plugs Guide for symptoms of worn plugs, why matching your exact plug specification matters, and trusted brands to buy from.

More Mazda Spark Plugs

The same part, covered across other Mazda models.