Are catalytic converter and catalyst converter the same thing?

Yes. "Catalytic Converter" and "Catalyst converter" refer to the same car part. Other common names include Catalyst converter, Catalyst Converter, Cat Converter. The part is the same regardless of which name is used.

How long does a catalytic converter last?

A well-maintained cat converter on a petrol car typically lasts 100,000–150,000 miles. Diesel oxidation catalysts often have shorter service lives due to soot contamination. Regular oil changes and addressing misfires promptly extend cat life.

Can I clean a catalytic converter instead of replacing it?

You can attempt a chemical clean using a fuel-additive cleaner designed for cats, and this sometimes recovers mild efficiency losses. A physically damaged, melted, or poisoned cat cannot be recovered — replacement is the only option.

Why is my new cat throwing a P0420 fault code?

P0420 can be triggered by lambda sensor faults upstream or downstream of the cat, as well as by the cat itself. Verify both oxygen sensors are functioning before condemning a new converter. On some vehicles an ECU reset is needed after cat replacement to allow the monitors to complete.

Will a catalytic converter affect my car's performance?

A healthy cat adds only a small amount of exhaust back-pressure and is undetectable in normal driving. A blocked cat drastically reduces power and fuel economy — addressing it restores performance.

Is catalytic converter theft an issue?

Yes, hybrid and high-ground-clearance vehicles are targeted due to their higher precious metal content. Anti-theft cat clamps and shields are available for commonly targeted models.

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Catalytic Converter buying guide — what to know before you buy

The catalytic converter — commonly called the cat, cat converter, or exhaust catalyst — is an exhaust after-treatment device containing a ceramic or metallic substrate coated with platinum, palladium, and rhodium. These precious metals catalyse the chemical conversion of harmful carbon monoxide, unburned hydrocarbons, and nitrogen oxides into carbon dioxide, water, and nitrogen. A failed cat causes an MOT failure on exhaust emissions, triggers lambda sensor fault codes, and can severely restrict exhaust flow if the substrate has collapsed. CarParts247 stocks direct-fit replacement catalytic converters from BM Catalysts, Bosal, Walker, and Klarius for a wide range of petrol and diesel vehicles.

Signs of a failing catalytic converter

A deteriorating cat gives several warning signs before it fails completely. Recognising them early prevents the cost of a new oxygen sensor or even engine damage from a collapsed substrate blocking the exhaust.

Check engine light with fault codes P0420 or P0430 (catalyst efficiency below threshold)
Sulphurous or 'rotten egg' smell from the exhaust — unburned sulphur from fuel
Rattling sound from under the vehicle — collapsed substrate fragments moving inside the can
Sluggish acceleration and high back-pressure from a blocked substrate
Failing the MOT emissions test (HC and CO above limits at idle and 2,500 rpm)

Why catalytic converters fail

Thermal damage is the leading cause. Misfires send unburned fuel into the exhaust, where it ignites inside the cat and melts the ceramic substrate. Oil burning and coolant leaks contaminate and poison the precious metal coating, destroying its catalytic activity.

Fix the root cause before fitting a new cat — fitting to a misfiring engine destroys the replacement quickly
Lead or silicone-contaminated fuel damages the catalyst coating irreversibly
Cold, short journeys prevent the cat from reaching its light-off temperature of ~250 °C, causing washout of catalytic coating over time
Physical impact from speed bumps or debris can crack the ceramic brick internally

OEM versus aftermarket catalytic converters

OEM catalysts from manufacturers such as BM Catalysts and Klarius carry Type Approval certification for UK and EU use, ensuring they meet the emissions standard applicable to the vehicle's registration date. Budget or non-Type-Approved units may fail the MOT's visual inspection if a EURO 5/6 vehicle is fitted with a converter lacking the correct approval markings.

Look for E-mark or British Standard approval on any aftermarket cat
Match the catalyst to the vehicle's emissions standard (EURO 3 through EURO 6d-TEMP)
Universal cats require custom pipework — direct-fit units are quicker to install and less prone to leaks