What is a Catalytic Converter?
A honeycomb filter that chemically cleans harmful gases out of the exhaust before they leave the bike.
Simplified animation — not to scale.
In plain English
Fitted on modern bikes to meet emissions rules, the catalytic converter uses precious-metal coated honeycomb to convert harmful gases into less harmful ones as exhaust passes through.
“A chemical scrubber sat in the exhaust stream, quietly cleaning up after every combustion event.”
How it works
As hot exhaust gas flows over the catalyst's coated surface, chemical reactions convert carbon monoxide and unburnt hydrocarbons into carbon dioxide and water vapour. It needs to reach operating temperature to work properly, which is part of why cold starts are dirtier than a fully warmed engine.
Signs of trouble
- ⚠Reduced performance from a blocked cat
- ⚠Rattling noise from a damaged internal honeycomb
- ⚠Failing an MOT emissions test
- ⚠Sulphurous 'rotten egg' smell from the exhaust
What affects the repair?
We don't publish a generic price for this part because a responsible estimate needs a named motorcycle and a recent quote. These are the factors a qualified technician will weigh up.
- •Diagnosis: intermittent or system-wide faults may need dealer-level tools before the actual part can be identified.
- •Accessibility: some parts are quick to reach; others require significant fairing, tank or engine-cover removal.
- •Model differences: prices and labour times vary widely between manufacturers and specification levels.
- •New vs used: a genuine OEM part fitted at a franchised dealer costs more than a serviceable used or aftermarket part.
- •Calibration / coding: some parts require post-fit calibration, coding or a road test, which adds labour time.
Technical review pending