Mercedes SLK200 / SLK250 R172 Filters and Spark Plugs: Buying Guide

For the early 1.8-litre M271 SLK200/SLK250 R172 petrol applications, MANN lists C 3210 for engine air filtration, HU 514 y for engine oil filtration and CUK 3621 for the cabin. NGK’s European catalogue lists PLKR7B8E, stock number 94716, for the M271.861 SLK200 and SLK250.

Coverage: early R172 SLK200 and SLK250 CGI/BlueEFFICIENCY petrol models with the 1,796 cc M271.861 engine. Match model type 172.448 (200) or 172.447 (250). Later 1,991 cc SLK200 M274, SLK250 CDI/diesel, SLK350, AMG and SLC models need their own application checks.

These are manufacturer catalogue references for the applications below. Match the vehicle and complete reference before ordering. A search result containing “R172” or “SLK250” can also refer to a different engine.

Parts references for the early petrol cars

MANN’s early petrol engine-filter rows run from March 2011 to June 2015. Use that as catalogue coverage alongside the model and engine identifiers, rather than a promise about every car registered in that period. The spark-plug catalogue’s date coverage is broader; the engine match remains essential.

Engine air filter: MANN C 3210

The engine air filter cleans the engine’s intake air. It is separate from the ventilation filter serving the cabin. In the current C 3210 product listing, MANN names both early petrol model types and the M271.861 engine.

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Check the listing’s complete part reference, seller and application information. A search can show similar-looking filters or alternatives. The later M274 SLK200 has a different catalogue row; do not transfer this engine air-filter choice on the strength of the SLK200 badge alone.

Cabin filter: MANN CUK 3621

MANN’s catalogue lists CUK 3621 as an activated-carbon cabin filter for the R172 SLK range. Its product information places it in the passenger area under the glove compartment. This identifies which filter a quotation should describe; it is not a complete removal and installation procedure.

Ask a garage to specify “cabin/pollen filter” on the invoice. That avoids confusing it with the engine air filter when a quote simply says “air filter”. When buying, match CUK 3621 and check the supplier’s vehicle selection rather than choosing another CUK number from a general Mercedes search.

Oil filter: keep the full suffix

MANN’s printed early petrol rows and the current HU 514 y page support that reference. MANN also has a separate new HU 514/1 y listing that includes SLK200. The reviewed information does not establish a universal replacement relationship between those references, so this page does not describe them as interchangeable.

If a supplier offers a different suffix, have it confirm the current application or supersession against the car. A similar dimension or a shortened “HU 514” description is not enough to settle that choice.

For oil-filter shopping, add or select the exact car on eBay, then check the individual listing’s reference and seller compatibility information before ordering.

The eBay category link is an affiliate link. It opens a broad browse page and does not certify every displayed item as suitable for this SLK.

Spark plugs: NGK PLKR7B8E / 94716

NGK’s European 2023 catalogue has separate SLK200 and SLK250 R172 1.8-litre rows naming M271.861 and PLKR7B8E / 94716. The UK 2024 catalogue corroborates that plug reference and lists four plugs for its grouped 1.8-litre SLK200/SLK250 entry.

When comparing prices, check whether the seller supplies one plug or a set of four. Match both the NGK part reference and stock number, and confirm the current vehicle application. An ignition fault should be diagnosed rather than treated as proof that a routine plug change will fix it.

This buying guide does not supply installation torque or a replacement procedure. Use instructions appropriate to the exact engine and plug, particularly if doing the job yourself.

When are they due?

Fitment and renewal timing answer different questions. Haynes UK’s public 250 BlueEFF petrol 271.861 summary gives air-filter and spark-plug renewal at 75,000 km or 48 months (about 46,600 miles). It is an indicative technical-publisher checkpoint for that named entry. Check the applicable Mercedes schedule and last renewal dates before deciding the work due.

No common cabin-filter interval or exact suffix checklist is inferred here. A garage should show which additional operations are due and which parts are included in the price.

Before you order

1. Confirm early 1.8-litre petrol, model type and M271 engine identity.
2. Read the entire manufacturer reference, including spaces, slash and suffix.
3. Check quantity per listing, seller and return terms.
4. Use the supplier’s vehicle check and ask it to resolve any conflicting application before purchasing.
5. Keep the invoice and record the date and mileage of renewal.

Continue with the SLK petrol engine-oil guide or return to the SLK200/SLK250 R172 maintenance guide.

Explore the Mercedes maintenance hub and our SLK R172 diagnostic scanner guide.

Sources and applicability

• MANN-FILTER 2024–26 catalogue, printed page 235 / PDF page 291: engine and cabin application rows.
• MANN C 3210 current product catalogue.
• MANN HU 514 y current product catalogue and separate HU 514/1 y listing.
• MANN CUK 3621 product information.
• NGK European 2023 catalogue, printed page 310 / PDF page 314 and NGK UK 2024 catalogue, printed page 48 / PDF page 50.
• Haynes UK SLK maintenance summary: named 250 BlueEFF petrol table only.

Checked 20 October 2026. Manufacturer references establish the stated catalogue applications; supplier searches are not fitment guarantees.

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