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Mercedes C-Class: no spark plug has been established for the petrol variants of this car. We will not publish a part number we cannot source. Search on Amazon
Spark plugs are set by the engine, not the model badge — the full per-engine breakdown, the diesel and electric variants and our sourcing notes are below.
Spark Plug Specifications
No single spark plug covers the Mercedes C-Class. The table below gives the plug for each engine in the range, because the plug follows the engine, not the model badge. Check which engine you have before ordering — the parts are not interchangeable, and on several cars in this class the gap differs too.
| Engine | Spark plug | Electrode gap | Plugs needed | OE number |
|---|---|---|---|---|
| All M254 petrols (C180, C200, C300, C300e) and M139.580 (AMG C43) | No data available — nothing established | — | 4 | No data available |
| OM654M diesels (C220d, C300d, C300de) | Glow plugs — this engine has no spark plugs | — | — | — |
Recommended Spark Plugs for Mercedes-Benz C-Class
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- Commonly mis-listed: NGK PLKR7A. It belongs to the older M271, M272 and M273 engines built between 2004 and 2016, not to any engine in this car,, so it is not the right part for this car.
Checked against: NGK, Denso, Bosch and Champion catalogue data via the TecDoc-derived application database, cross-checked against manufacturer OE numbers where those are published.
A note on quantity: the catalogue quantity field is unreliable — it prints 4 for a number of three-cylinder engines. The quantities in the table above have been corrected to the actual cylinder count.
Diesels and Electric Variants
Diesel variants of the Mercedes C-Class have glow plugs, not spark plugs. A compression-ignition engine has no spark at all: the glow plug is a heater that warms the combustion chamber for cold starting, and it is a different part with a different service life. Nothing in the spark plug table applies to a diesel.
Recommended Spark Plugs
Find your engine code first
Order by stock number, not by name
Buy a full set
How Often to Change Them
We are not publishing a mileage figure for this car, because we could not source one. No manufacturer service interval was found for any of the vehicles in this guide, and we will not print a number we cannot attribute.
The figures that circulate online mostly come from parts-catalogue “recommended intervals”, and those contradict each other on cars that share an engine — the same 1.0 T-GDi appears at 75,000 km on one model page and 30,000 km on another; the same Stellantis 1.2 turbo appears at 10,000 km on one and 30,000 km on another. Those are catalogue defaults, not manufacturer schedules, and quoting them as though they were would be dishonest.
The figure that governs your car is in the service schedule in the handbook, or in the manufacturer’s online service planner. As a practical matter, replace plugs sooner than the schedule if the engine misfires under load, idles roughly, is slow to start, or fuel consumption has crept up without another explanation.
Frequently Asked Questions
What spark plugs does a Mercedes C-Class use?
No data available. We could not establish a spark plug for any petrol variant of the Mercedes C-Class from the catalogues we check, and we will not publish a part number we cannot source.
How many spark plugs does a Mercedes C-Class need?
Not published for this car in the data we checked. One plug per cylinder is the rule, so count the coil packs or the plug leads.
Do diesel Mercedes C-Class models use spark plugs?
No. Diesel engines use glow plugs, which are heaters for cold starting, not igniters. A diesel has no spark plugs at all, and none of the parts in the table above apply to one.
How often should spark plugs be changed on a Mercedes C-Class?
Follow the service schedule in your handbook. We deliberately do not publish a mileage figure here: no manufacturer interval could be sourced for this car, and the figures that circulate come from parts-catalogue defaults that contradict each other across models sharing the same engine. Change plugs sooner than the schedule if the engine misfires under load, idles roughly or is slow to start.
Can I use a different brand of spark plug in a Mercedes C-Class?
Yes, provided the replacement matches the original on thread size, reach, heat range, seat type and electrode material, and is gapped to the figure in the table. Cross-reference by the OE number rather than by the model name — that is the reference that identifies the part unambiguously. Do not fit a plug of a different heat range because it looks similar or shares part of the type code.
Other Mercedes-Benz C-Class Guides
How we check fitment for this guide
We cross-reference fitment figures against manufacturer specifications and OE-supplier catalogue data where available, and matched to the standard codes that actually govern fit — battery type/group sizes, wiper lengths and fitting types, bulb fitment codes, tyre size markings, and oil specifications. We work by make, model, year, engine, and build date, because a single model can take different parts across its life. Where the right part depends on your exact vehicle, we tell you to confirm by registration or VIN. More on our method →