Exhaust Manifold Header with Catalytic Converter for Nissan Altima (2007-2012) 2.5L

Direct-Fit Exhaust Manifold Header with Catalytic Converter for 2007-2012 Nissan Altima (L32)

What it Does: The Exhaust Manifold Header with Catalytic Converter replaces the failed factory manifold on the 2007-2012 Nissan Altima to eliminate exhaust leaks, restore accurate upstream AFR readings, and maintain EPA OBD-II emissions compliance.

The Stock Nissan Altima Manifold Cracking Problem

The factory cast-iron manifold on the QR25DE is notorious for structural thermal fatigue. Cyclic expansion and contraction stress the thin cast runners directly above the catalytic converter substrate, yielding hairline stress fractures near the cylinder head flange. These fractures introduce ambient oxygen ahead of the primary air-fuel ratio sensor, falsifying fuel trims, causing rough idle, and triggering false lean trouble codes (P0171, P0420). Additionally, disintegrated internal ceramic washcoat risks catastrophic cylinder back-siphon during valve overlap.

The Engineering Solution

This replacement assembly eliminates cast-iron brittleness by utilizing heavy-gauge, mandrel-bent stainless steel tubular runners TIG-welded to a precision-machined, warp-resistant mounting flange. Smooth tubular geometry minimizes boundary-layer turbulence and reduces backpressure relative to rough OEM castings. The integrated high-flow ceramic substrate meets federal EPA and OBD-II monitoring parameters. Built to match OEM part numbers 753006, 40800, and 641302, it retains factory mounting geometry, the pre-converter O2 sensor bung, and the OEM 3-bolt lower flange connection.

What's Included

• 1 Exhaust Manifold Header with Integrated Catalytic Converter
• Manifold and Flange Gaskets
• Exhaust Studs

Technical Specifications

Compatibility

• 2007-2012 Nissan Altima 2.5L 4-Cylinder Sedan (Base, S, SL)
• 2008-2012 Nissan Altima 2.5L 4-Cylinder Coupe (S)

Frequently Asked Questions & Fitment Warnings

Does this fit the L32 Altima?

Yes, this is a direct fit for the 2007-2012 Nissan Altima equipped with the QR25DE engine. Non-CARB compliant; not legal for sale or use in California, Colorado, New York, or Maine on CARB emissions-equipped vehicles. Does not fit 3.5L V6 (VQ35DE) models.

What torque sequence should be used during installation?

Clean the cylinder head mating surface completely, torque new fasteners from the center cylinders outward in two stages to prevent flange warpage, and retorque hardware following the first full thermal cycle.

The Nissan QR Performance Standard

Engineered to withstand the intense thermal cycles of high-compression Japanese 4-cylinders, this manifold restores proper backpressure dynamics, eliminates exhaust cabin intrusion, and delivers clean, leak-free exhaust velocity.