Catalytic Converter for Jeep Grand Cherokee (2001-2004) 4.0L Front

Direct-Fit Front Catalytic Converter for 2001-2004 Jeep Grand Cherokee (WJ)

What it Does: The front catalytic converter replaces deteriorated factory exhaust pre-converters on the 2001-2004 Jeep Grand Cherokee to eliminate P0420/P0430 diagnostic trouble codes, restore exhaust scavenging, and maintain legal EPA tailpipe emissions.

The Stock Jeep Grand Cherokee Exhaust Degradation

Factory exhaust downpipe assemblies on the WJ generation suffer from severe thermal cycling fatigue and internal ceramic washcoat sintering over extended mileage. In the 4.0L PowerTech inline-six, exhaust pulses and unburned hydrocarbons gradually foul the factory dual pre-catalyst bricks, leading to reduced cross-sectional flow area, elevated exhaust backpressure, and upstream heat retention at the cylinder head exhaust ports. Furthermore, aged factory flanges and thin-gauge pipe sections commonly develop micro-fissures adjacent to the oxygen sensor bungs, causing false lean readings and persistent check engine lights.

The Engineering Solution

Constructed from heavy-gauge, corrosion-resistant stainless steel, this front catalytic assembly delivers precise flow characteristics without requiring cutting or custom torch work. The unit houses a high-efficiency ceramic substrate loaded with precious metals optimized to clean unburned hydrocarbons and carbon monoxide while minimizing backpressure. CNC-machined, thick-wall connection flanges prevent thermal warping, and precision-located, TIG-welded O2 sensor bungs allow factory downstream sensors to thread in without harness tension. The mandrel-bent downpipe routing maintains laminar exhaust velocity, restoring proper low-end torque dynamics across the entire rev range.

Technical Specifications

Compatibility

• 2001 Jeep Grand Cherokee 4.0L Inline-6 (WJ Chassis) - Front
• 2002 Jeep Grand Cherokee 4.0L Inline-6 (WJ Chassis) - Front
• 2003 Jeep Grand Cherokee 4.0L Inline-6 (WJ Chassis) - Front
• 2004 Jeep Grand Cherokee 4.0L Inline-6 (WJ Chassis) - Front
• Note: Fits 4.0L I6 only; does not fit 4.7L V8 applications. EPA compliant (46-state legal; not legal for sale/use in CA, NY, CO, or ME).

Frequently Asked Questions

Does this fit the WJ Grand Cherokee?

Yes, this is a direct fit for the 2001-2004 Jeep Grand Cherokee equipped with the 4.0L PowerTech inline-six engine.

Will this direct-fit converter resolve catalytic efficiency trouble codes like P0420?

Yes, providing upstream air-fuel ratios and sensors are operating within factory spec, the new ceramic catalyst restores conversion efficiency to clear P0420 and P0430 codes.

The Jeep Off-Road Standard

Built to handle harsh underbody vibration, frame flex, and severe trail washboard, this stainless steel assembly delivers the rugged mechanical durability and steady low-rpm torque essential for dependable off-road crawling and towing.