Catalytic Converter for Jaguar XJR (2004-2009) 4.2L

Direct-Fit Dual Catalytic Converter Set for 2004-2009 Jaguar XJR (X350)

What it Does: This direct-fit dual catalytic converter set replaces both factory bank converters on the 2004-2009 Jaguar XJR (X350) equipped with the AJ33S/AJ34S 4.2L Supercharged V8 to restore exhaust flow and convert HC, CO, and NOx emissions.

The Stock Jaguar XJR Catalyst Failure

On the X350 chassis powered by the supercharged AJ33S/AJ34S 4.2L Supercharged V8, high exhaust gas temperatures under boost subject the factory catalytic converters to severe thermal cycling. Over time, thermal fatigue and rich-condition heat soak fracture the OEM ceramic substrate and degrade the precious-metal washcoat. Once the internal monolith breaks loose or partially melts, exhaust flow becomes restricted and downstream oxygen sensors detect oxygen storage loss, triggering P0420 or P0430 catalyst-efficiency faults.

Common Symptoms of a Failing OEM Catalytic Converter

• Check Engine Light / DTCs: Triggers P0420 (Bank 1) or P0430 (Bank 2) catalyst system efficiency below threshold codes when washcoat oxygen storage fails.
• Metallic Exhaust Rattle: Audible rattling or buzzing beneath the floorpan at idle and deceleration caused by a fractured ceramic core vibrating inside the canister.
• Exhaust Backpressure & Emissions Failure: Restricted substrate channels choke supercharged V8 exhaust scavenging, reducing top-end power and causing failed OBD-II readiness or tailpipe emissions tests.

The Direct-Fit Stainless Exhaust Solution

Engineered as a complete pair, these replacement converter pipes feature corrosion-resistant stainless steel bodies and tubing built to withstand supercharged exhaust heat without cracking. Each unit houses a high-efficiency ceramic honeycomb substrate coated with precious metals to restore proper HC, CO, and NOx conversion for OBD-II compliance. Factory-style flanges and precision-welded O2 sensor bungs ensure an exact bolt-on fit (8-inch body length, 5-inch height) with zero cutting or welding required.

What's Included

• 2 x Catalytic Converter Pipes

Technical Specifications

Compatibility

• 2004 Jaguar XJR 4.2L Supercharged V8
• 2005 Jaguar XJR 4.2L Supercharged V8
• 2006 Jaguar XJR 4.2L Supercharged V8
• 2007 Jaguar XJR 4.2L Supercharged V8
• 2008 Jaguar XJR 4.2L Supercharged V8
• 2009 Jaguar XJR 4.2L Supercharged V8

Frequently Asked Questions & Fitment Warnings

Does this fit the X350 XJR?

Yes. This is a direct fit for the 2004-2009 Jaguar XJR equipped with the AJ33S/AJ34S 4.2L Supercharged V8 engine. Does not fit 2010+ XJR 5.0L models. This is an EPA federal converter and is not CARB approved—not legal for vehicles registered in California, New York, Colorado, or Maine.

Will this clear P0420/P0430 codes, and are O2 sensors included?

Yes, if the fault stems from failed catalysts; oxygen sensors are not included. Replacing both degraded converters restores proper oxygen storage capacity to clear P0420 and P0430 codes, provided you transfer functional factory O2 sensors (or install new ones) and verify zero upstream exhaust leaks.

What preparation is required for bolt-on installation?

Allow the exhaust to cool completely and soak all flange fasteners with penetrating oil beforehand. Unbolt the factory converter pipes, install both new units using new flange gaskets, torque all fasteners evenly, and inspect every joint for leaks at startup; professional installation is recommended.

The Jaguar Precision Standard

Maintaining emissions compliance and crisp supercharged response on the X350 platform demands exact-fit exhaust components engineered for factory ECU tolerances. Installing both stainless converter pipes together restores balanced bank-to-bank backpressure and ensures trouble-free, CEL-free operation.