40919 40800 KAX Front and Rear Catalytic Converter Fits Altima 2.5L

In this review of the 40919 40800 KAX catalytic converter set, the bottom line is simple: this replacement is aimed at owners of 2007-2013 Nissan Altima 2.5L who need an EPA-compliant, durable catalytic solution that restores emissions performance and quiets the exhaust. The single biggest reason to consider this set is its combination of EPA-certified high flow design and heavy-duty stainless steel construction, which together seek to balance conversion efficiency with long-term durability for everyday driving and highway use.

Key Features

• Fitment: Designed specifically for 2007-2013 Nissan Altima 2.5L applications to replace worn or failed factory converters.
• EPA and OBD3 compliance: Produced under strict procedures to meet EPA and OBD3 standards for legal road use in most states.
• High flow performance: The internal design aims to increase conversion efficiency and vehicle power without sacrificing exhaust flow rate.
• Stainless steel shell: Heavy-duty stainless outer shell and firm welds provide resistance to heat and pressure for extended service life.
• Ceramic substrate: Internal ceramic substrate with high-load precious metals improves pollutant purification and restores quieter operation.

Who It's For

This catalytic converter set is best for DIY mechanics and independent repair shops working on 2007-2013 Altima 2.5L models who need a direct replacement that meets EPA and OBD3 guidelines. It suits owners who want a higher flow unit that may improve throttle response and help clear an emissions-related check engine light when the factory converter has failed.

Buyers in states with stricter emission requirements such as California, Colorado, New York, and Maine should look elsewhere because sales are not carried out for those locations. Also, drivers who require an exact OEM fit right out of the box should be aware that some customers reported mixed fit and alignment results and may prefer sourcing directly from a dealer for guaranteed OEM dimensions.

Pros & Cons

Pros

• EPA-certified high flow design improves conversion while maintaining exhaust flow.
• Durable stainless steel outer shell with firm welds resists heat and extends life.
• Quality ceramic substrate with precious metal loading enhances purification.
• Good value compared with a full dealer replacement for many buyers.

Cons

• Fit and alignment have mixed reports; O2 bung location or dimensions may require adjustment on some vehicles.
• Several customers noted missing hardware such as bolts and gaskets, which may require additional purchases.

Specifications

Vehicle fitment	2007-2013 Nissan Altima 2.5L
EPA/OBD	EPA certified, OBD3 compliant
Construction	Stainless steel outer shell
Internal substrate	Ceramic with high-load precious metal catalyst
Design focus	High flow performance
Includes	Front and rear catalytic converters (2 pieces)

Our Verdict

The KAX 40919 40800 catalytic converter pair is a practical, cost-conscious replacement for 2007-2013 Altima 2.5L owners who need an EPA-certified high flow option with robust stainless construction. It delivers solid emissions control and durability for most drivers, but double-check fitment and be prepared to source small hardware if alignment or bolts are missing.

Frequently Asked Questions

Will this set work for my 2009 Altima 2.5L?
Yes, this catalytic converter set is specified to fit 2007 through 2013 Altima 2.5L models.

Is it legal for road use?
The converters are produced to meet EPA and OBD3 standards, but they are not sold for use in states with stricter emission rules such as California, Colorado, New York, and Maine.

Do I get bolts and gaskets with the converters?
Some customers reported missing hardware; verify included parts with the seller and have replacement bolts or gaskets available if needed.