Exhaust & emissions

SCR catalyst

Helps reduce nitrogen oxides using a controlled reducing-agent system.

Where it sits

Within the exhaust after-treatment assembly on equipped diesels.

How it works

Injected urea solution produces ammonia used in the catalyst’s reduction reactions.

Think of it as

A chemical finishing station for diesel exhaust.

Symptoms when it fails

Emissions warnings can arise from dosing, fluid quality, sensors or catalyst performance.

Lifespan

Condition, contamination, operating pattern and the underlying engine matter more than a universal age limit.

Repair cost

Sensors and joints differ greatly from complete after-treatment assemblies. First repair the cause of contamination or abnormal combustion.

The BMW angle

BMW BluePerformance equipment is engine- and market-dependent rather than universal to all diesels.

Used in

BMW diesel models fitted with SCR after-treatment; verify the specific engine and market.

Sources
Same system

Exhaust & emissions