Catalytic Converter for Mazda B-Series (1998-2000) 3.0L 4.0L Rear

Direct-Fit Rear Catalytic Converter for 1998-2000 Mazda B-Series (UN Platform)

What it Does: The rear catalytic converter restores exhaust scavenging efficiency, neutralizes exhaust gas emissions, and resolves catalytic degradation codes on 1998-2000 Mazda B-Series trucks without requiring custom exhaust fabrication.

The Stock Mazda B-Series Substrate Degradation

Factory exhaust converters on high-mileage UN chassis trucks regularly succumb to thermal shock and internal washcoat attrition. Paired with prolonged operational heat cycles, the factory ceramic cores on the Vulcan 3.0L and Cologne 4.0L engines break down and choke off downstream flow. This internal core melting or fragmentation induces restrictive backpressure, spikes cylinder head temperatures, diminishes engine power under load, and illuminates persistent P0420 diagnostic trouble codes.

The Engineering Solution

Engineered as a bolt-in replacement for factory interchange 23541, this rear converter assembly utilizes high-grade stainless steel outer tubing to withstand corrosion and road brine. Inside, a durable ceramic honeycomb substrate features an optimized washcoat formula to maximize precious metal surface contact, oxidizing hydrocarbons and carbon monoxide without constricting exhaust flow. Laser-cut direct-fit flanges ensure leak-free seal integrity to stock factory downpipes and intermediate exhaust piping.

Technical Specifications

Compatibility

• 1998-2000 Mazda B-Series B3000 (3.0L V6)
• 1998-2000 Mazda B-Series B4000 (4.0L V6)
• Rear position application only (Does not fit B2500 2.5L L4 models)

Frequently Asked Questions

Does this fit the UN Platform B-Series?

Yes, this is a direct fit for the 1998-2000 Mazda B-Series equipped with the Vulcan 3.0L or Cologne 4.0L engine.

Is this catalytic converter legal for road use in California?

No, this unit is EPA 46-state compliant and cannot be sold, registered, or shipped to California, New York, Colorado, or Maine.

The Mazda Truck Durability Standard

Work-ready trucks depend on continuous exhaust flow to maintain pulling power; this stainless converter preserves factory exhaust gas velocity and thermal reliability under sustained towing loads.