BMW 1 Series Spark Plugs: Intervals, Fitment & Warning Signs
On the 1 Series, related engines have genuinely had a confirmed bulletin addressing a fault where the engine fails to restart after a cold start.
Illustration for editorial purposes
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OEM Part Number: confirm via engine code — aftermarket NGK 91469 / Bosch 0 242 140 507
| Petrol engines in this generation | 116i 109 HP; 118i 136 and 140 HP; 120i 178 and 192 HP; 128ti 245 and 265 HP; M135i xDrive 306 HP |
|---|---|
| Spark plugs (aftermarket) | NGK 91469 (iridium, gap 0.75 mm, 14 mm hex, M12x1.25, 28.5 mm reach); NGK 95248 (iridium, 14 mm Bi-Hex, M12x1.25, 28.5 mm); NGK 94201 (iridium, 14 mm Bi-Hex, M12x1.25, 26.5 mm); NGK 97506 (iridium, 14 mm Bi-Hex, M12x1.25, 27.5 mm); Bosch 0 242 140 507 (gap 0.7 mm, M12x1.25); Bosch 0 242 145 555 (gap 0.8 mm, M12x1.25); Champion OE259 and OE274 (iridium, gap 0.74 mm, 14 mm Bi-Hex, M12x1.25, 25.5 mm); Denso IK20TT (iridium centre, platinum earth, M14x1.25, 19 mm) |
| Genuine (OE) numbers quoted | Denso K20TT quotes OE 1WT318110 (alternatives IK20, IK20TT) |
| Fitment notes | Match thread size, heat range and gap to the engine code. |
BMW 1 Series Spark Plugs: A Cheap Part That Causes Expensive-Feeling Problems
On the BMW 1 Series, spark plug wear tends to creep in quietly — idle gets a little rougher, throttle response softens slightly — the kind of symptoms that get blamed on almost anything else under the bonnet. Given how cheap the part itself is, it's an easy one to put off for longer than makes sense.
BMW 1 Series Spark Plugs: What They Do
Inside each cylinder of the BMW 1 Series, spark plugs ignite the compressed fuel-air mixture, and their condition has a direct effect on combustion efficiency, fuel economy and how smoothly the engine runs. Petrol engines can't function without them; diesels don't use spark plugs, relying on compression alone to ignite fuel.
BMW 1 Series Spark Plugs: Generations, Engines & Spark Plug Count
| Diesel variants | Not applicable — diesel engines use compression ignition and have no spark plugs at all |
|---|---|
| Petrol four-cylinder (most trims) | 4 spark plugs — one per cylinder |
| Petrol six-cylinder (M-Performance trims, where fitted) | 6 spark plugs — a genuinely different engine family (BMW's inline-six) from the standard four-cylinder units, not a bored-out version of the same engine |
BMW 1 Series Spark Plugs: Watch: Replacing It
F20/F21 1 Series; for F40 120i B48 see G20 330i B48 video https://www.youtube.com/watch?v=Go3s18ZTFFQ
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A Genuinely Useful Piece of Context Worth Knowing About Misfires — BMW 1 Series Spark Plugs
If the engine has turned over but failed to actually start on a repeated cold-start attempt, this is genuinely worth knowing: related BMW engines have had a confirmed technical bulletin addressing exactly this fault, caused by unfavourable software combined with the original spark plug part, since superseded twice with revised versions.
It's also genuinely worth knowing that coil packs have been documented failing even on cars with genuinely low mileage, and that the official service interval has been considered too long by experienced specialists on related engines, with actual testing suggesting a shorter interval in practice.
BMW 1 Series 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 BMW Spark Plugs
The same part, covered across other BMW models.