Catalytic Converter for Nissan Altima (2002-2006) 2.5L Rear

Direct-Fit Rear Catalytic Converter for 2002-2006 Nissan Altima (L31)

What it Does: The rear catalytic converter assembly restores factory exhaust scavenging and tailpipe emissions compliance on the 2002-2006 Nissan Altima 2.5L to eliminate recurring P0420 trouble codes and prevent exhaust leaks.

The Stock Nissan Altima L31 Exhaust Breakdown

The third-generation L31 Altima chassis frequently suffers from mechanical failure at the undercar exhaust junction. The factory mid-pipe flex section is prone to fatigue cracking, salt corrosion, and internal braid unraveling from persistent engine rock on the transverse QR25DE mounts. Once the stock flex braid splits, high-frequency resonance and unmetered exhaust leaks trigger downstream sensor faults. Simultaneously, aged factory ceramic washcoats degrade over time, losing conversion efficiency and causing catalytic substrate breakdown that impairs backpressure dynamics and engine breathing.

The Engineering Solution

This direct-replacement rear assembly resolves these structural and emissions failures using heavy-duty stainless steel tubing joined to a multi-rib flex coupling engineered to isolate engine vibrations. The interior houses an EPA-grade high-flow ceramic monolith substrate formulated with targeted precious metal washcoats to maintain continuous hydrocarbons (HC) and carbon monoxide (CO) reduction without creating exhaust flow restrictions. Precision-machined, thick-gauge mounting flanges ensure leak-free seal retention against OE mating surfaces, while integrated mounting points install directly to the stock hangars without cutting or custom fabrication.

Technical Specifications

Compatibility

• 2002-2006 Nissan Altima Base Sedan 4-Door 2.5L 2488CC l4 GAS DOHC Naturally Aspirated
• 2002-2006 Nissan Altima S Sedan 4-Door 2.5L 2488CC l4 GAS DOHC Naturally Aspirated
• 2002-2006 Nissan Altima SL Sedan 4-Door 2.5L 2488CC l4 GAS DOHC Naturally Aspirated
• Note: Fits 2.5L 4-cylinder models only; does not fit 3.5L V6 applications. 48-state legal (not legal for sale or use in CA or NY).

Frequently Asked Questions

Does this fit the L31 Altima?

Yes, this is a direct fit for the 2002-2006 Nissan Altima equipped with the QR25DE engine.

Does this unit clear downstream P0420 catalytic efficiency DTCs?

Yes, its high-efficiency ceramic substrate restores factory exhaust conversion efficiency to clear catalytic fault codes when downstream sensors are operating correctly.

The Nissan JDM Standard

Keep your QR25DE breathing cleanly with an exhaust assembly built to withstand high exhaust gas temperatures while delivering crisp throttle response, proper acoustic dampening, and reliable OBD-II emissions readiness.