BMW 4 Series Spark Plugs: Intervals, Fitment & Warning Signs
On the 4 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 91874 / Bosch 0 242 145 515
| Petrol engines in this generation | 418i 136 HP; 420i 163 and 184 HP; 425i 184 HP; 428i 245 HP; 430i 249 and 252 HP; 435i 306 and 340 HP; 440i 326 and 360 HP; M4 431 HP, M4 Competition 450 HP, M4 CS 460 HP, M4 GTS 500 HP |
|---|---|
| Spark plugs (aftermarket) | NGK 91874 (iridium, gap 0.8 mm, 14 mm, M12x1.25, 26.5 mm); NGK 94201 (iridium, M12x1.25); NGK 97506 (iridium, M12x1.25, 27.5 mm); Bosch 0 242 145 515, 0 242 145 541 and 0 242 145 555 (gap 0.8 mm, M12x1.25); Champion OE242 and OE243 (platinum, gap 0.8 mm, 14 mm Bi-Hex, M12x1.25); Champion OE245 and OE259 (iridium); Denso SXB24HCF-D7 (iridium centre, platinum earth, M12x1.25); Beru Z364 and Z366 (iridium centre, platinum earth, gap 0.8 mm, M12x1.25) |
| Genuine (OE) numbers quoted | Denso SXB24HCF-D7 quotes OE 12 12 0 050 948 |
| Fitment notes | Every plug on the list is a 14 mm hex, M12x1.25 type, with iridium the norm and Champion's OE242 and OE243 as platinum; no engine codes are tied to individual plugs. |
BMW 4 Series Spark Plugs: A Cheap Part That Causes Expensive-Feeling Problems
A worn set of spark plugs in the BMW 4 Series doesn't make itself obvious: idle roughens slightly, acceleration loses a bit of urgency, and both symptoms are easy to blame on something else entirely. Given how inexpensive the part is, it often gets neglected for far longer than it should.
BMW 4 Series Spark Plugs: What They Do
Every combustion cycle in the BMW 4 Series's petrol engine starts with a spark plug igniting the compressed fuel-air mixture, and their condition shapes efficiency, economy and smoothness directly. Diesel versions don't need them at all, relying purely on compression to ignite fuel.
BMW 4 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 4 Series Spark Plugs: Watch: Replacing It
F32 435i N55 six-cylinder
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A Genuinely Useful Piece of Context Worth Knowing About Misfires — BMW 4 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.
BMW 4 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.