Carautonomy — car parts and warning lights explained
← All car parts
Exhaust

What is a Catalytic Converter?

A clever filter that scrubs harmful gases out of your exhaust.

CATALYTIC CONVERTER — 3-WAY REACTIONCO · HC · NOₓDirty exhaustCO₂ · H₂O · N₂Clean gasO₂O₂Catalyst ~400–800°CCeramic honeycomb · Pt/Pd/Rh coatingHot exhaust passes the coated honeycomb → harmful gases react → clean gas out

Simplified animation — not to scale.

In plain English

Bolted into the exhaust system, the 'cat' uses precious metals (platinum, palladium, rhodium) to convert toxic gases like carbon monoxide into less harmful ones.

A simple analogy

"An air-purifier for your exhaust — pollutants go in, cleaner air comes out."

How it works

Hot exhaust gases pass through a honeycomb coated in catalyst metals. Chemical reactions on the surface turn pollutants into water vapour, CO₂, and nitrogen.

Signs of trouble

  • Rattling noise from underneath
  • Rotten egg smell from the exhaust
  • Failed MOT emissions
  • Sluggish acceleration
Rough UK cost

£400 – £1,500+ (often the most expensive exhaust part)

Always get a written quote. Prices vary by car, region, and parts brand.

Heads up: Carautonomy is for general guidance only. If your car is showing warning lights or behaving oddly, get it looked at by a qualified mechanic.

Keep exploring