Catalytic converter
Helps convert certain exhaust pollutants into less harmful gases.
In the exhaust, often close to the engine for warm-up.
Catalyst-coated surfaces promote reactions when operating conditions and mixture are suitable.
A chemical cleanup station in a hot gas stream.
Efficiency faults can involve exhaust leaks, sensors or engine problems as well as the catalyst.
Condition, contamination, operating pattern and the underlying engine matter more than a universal age limit.
Sensors and joints differ greatly from complete after-treatment assemblies. First repair the cause of contamination or abnormal combustion.
Misfires can damage a BMW catalyst, so replacing it without fixing combustion may repeat the failure.
BMW combustion models; petrol and diesel after-treatment components differ by engine and market.