Second Hand Mercedes-Benz CLS Glow Plugs

Yes, but only the diesel-engined CLS variants have glow plugs — these are a diesel-only component used to pre-heat the combustion chamber for cold starts. Petrol CLS models (including all AMG petrol variants) use spark plugs instead and never had glow plugs fitted. If you're unsure which fuel type your CLS is, check your V5C or run a VIN check before searching.

The CLS has run across two main generations: the W219 (2004–2010) and the W218 (2011–2018), with the C257 third generation launching from 2018 onwards. Diesel variants with glow plugs were available across all three generations, with engine codes such as OM642 (3.0 V6 diesel) and OM651 (2.1 four-cylinder diesel) appearing in the W218 and C257. The W219 also offered diesel variants in certain markets, though UK diesel supply was more limited on that generation.

Almost certainly not as a straight swap — the W219 and W218 use different diesel engine families, and glow plug fitment follows the engine code rather than the generation or body style. The key detail is your exact engine code, which you'll find on your V5C or via a VIN check; supply this to the breaker so they can confirm whether plugs from their donor vehicle match yours. Never assume cross-generation compatibility without verifying the engine codes match.

No — trim level has no bearing on glow plug fitment whatsoever. Whether your CLS is a standard Sport, AMG Line, or any other trim designation, what matters entirely is the engine code, as the same diesel engine unit is shared across trim levels. Your breaker will match on engine code, not trim, so focus on supplying that detail rather than the trim name.

Both the 2012 and 2014 CLS 250 CDI fall within the W218 generation (2011–2018) and typically use the OM651 four-cylinder diesel engine, which suggests the glow plugs are likely to be the same part. However, confirm the engine code on both vehicles matches exactly before purchasing, as ancillary specifications can vary within a generation and the breaker should verify compatibility against your registration. Engine code is the definitive check here, not the year alone.

A four-cylinder CLS diesel (such as the OM651 in the 250 CDI) requires four glow plugs, while a V6 diesel (such as the OM642 in the 350 CDI) requires six — one per cylinder. Position within the engine doesn't affect which plug you need, as all cylinders in a given engine use the same specification plug. It's worth replacing the full set rather than individual plugs, as worn plugs on a used engine are best swapped out together for reliable cold starting.