Used Ford Fiesta Catalytic Converter

This is an important boundary to check: the Mk6 Fiesta ran from 2002 to 2008, and the Mk7 launched in 2008, so a 2010 and a 2012 car are both Mk7 — on the face of it from the same generation. However, whether the catalytic converter actually interchanges depends on the engine code and emissions standard of each car, and cat-specific interchange across even minor production changes is strong confirm-with-breaker territory, so give the breaker both registrations and let them verify against the engine codes before buying.

Trim level — Zetec, Titanium, Studio, or anything else — does not determine which catalytic converter a Fiesta needs; what matters is the engine code, fuel type, and the emissions era the car was built to. A cat listed for a Zetec with the same engine code and year as your Titanium is the same part, so don't filter by trim when searching. Be aware that other exhaust components around the cat may look slightly different between cars even when the cat itself matches, but that's a cosmetic rather than a fitment issue.

No — the Fiesta ST uses a different, higher-output engine (the 1.6 EcoBoost on the Mk7 ST180, for example) rather than the 1.0 EcoBoost three-cylinder, so the exhaust systems are built around entirely different engines and the cats will not interchange. Always match the catalytic converter to the specific engine code in your car, not just the model name. Confirm the exact part with a breaker using your registration so they can check engine code to engine code.

The Mk7 Fiesta received a facelift in 2013, often referred to as the Mk7.5, so a 2014 car is a facelifted Mk7. Whether the facelift changed the catalytic converter for your specific engine depends on the engine code and any Euro emissions standard update applied at the same time, and whether a pre-facelift cat crosses that 2013 boundary is exactly the kind of interchange detail to confirm with the breaker against both registrations rather than assume.

No — petrol and diesel exhaust aftertreatment systems are fundamentally different; diesel Fiestas use a different catalyst chemistry and are more likely to also have a diesel particulate filter (DPF) in the system, which petrol Fiestas do not. Fitting a cat from the wrong fuel type will not work correctly and is likely to cause an MOT failure. Always source a catalytic converter matched to your fuel type and engine code.

Visual similarity is not a reliable guide — exhaust systems follow the engine specification and the emissions standards (such as Euro 5 or Euro 6) that applied when the car was built, and a cat from the wrong emissions era may not fit the mounting points correctly or may cause your Fiesta to fail its MOT emissions test even if it bolts on. The Mk7 Fiesta generation spans 2008 onwards, and emissions standard changes occurred within that period, so year matters as well as generation. Give the breaker your registration and ask them to match engine code to engine code to be safe.