Used Mercedes-Benz ML Catalytic Converter

The ML ran across three generations — the W163 (1998–2005), the W164 (2005–2011), and the W166 (2011–2019) — and catalytic converters are not interchangeable across these generations due to differences in engine architecture and emissions standards. Even within a generation, the emissions era matters: the shift to Euro 5 and later Euro 6 brought different catalyst specifications, and fitting a unit from the wrong era could cause an MOT failure. Whether a specific cat from one generation or emissions band will cross to another is strong confirm-with-breaker territory — give the breaker your registration so they can check against the exact engine code and emissions spec.

The W164 (2005–2011) and W166 (2011–2019) are completely different generations with different engines, exhaust routing, and emissions calibration, so a direct swap is very unlikely. The W166 also sits firmly in the Euro 5 and Euro 6 era, meaning the catalyst chemistry and configuration differ from the older W164 units. Always confirm interchange specifics with the breaker against your registration number rather than assuming physical similarity means compatibility.

Yes, all petrol-engined ML variants have a catalytic converter as standard, and diesel ML models also carry a diesel oxidation catalyst (DOC) as part of their exhaust aftertreatment system. Diesel variants from the W164 onwards also introduced a diesel particulate filter (DPF) alongside the oxidation catalyst, so on those cars you may be looking for both components. If you are unsure whether you need the cat, the DPF, or both, describe your symptoms to the breaker and quote your registration so they can identify the correct part.

Trim level — whether Sport, SE, AMG Line, or any other — has no bearing on which catalytic converter you need; what matters is the engine code, fuel type, and the emissions standard the car was built to. Two ML350 petrol models of the same year will take the same cat regardless of whether one is a Sport and the other an SE. Focus on matching the engine code and model year with the breaker rather than the trim badge.

No — petrol and diesel catalytic converters are fundamentally different in design and chemistry, and swapping between fuel types will not work and would cause an immediate MOT failure. Diesel ML models use a diesel oxidation catalyst (DOC), often paired with a DPF, while petrol models use a three-way catalyst; these are not interchangeable. Always make sure the breaker knows your fuel type alongside your registration when sourcing a replacement.

Year does matter within the W166 (2011–2019) generation because the switch from Euro 5 to Euro 6 emissions standards affected the exhaust aftertreatment specification, and a unit from the wrong emissions era may not pass MOT or may trigger warning lights. Engine code is equally important, as the W166 was offered with a range of petrol and diesel units that each have their own catalyst configuration. Give your registration and engine code to the breaker so they can confirm the correct spec rather than assuming any W166 cat will do.