Catalytic Converter for Pontiac Bonneville (1997-2005) 3.8L

Direct-Fit Stainless Catalytic Converter for 1997-2005 Pontiac Bonneville (H-Body / G-Body)

What it Does: This direct-fit underbody catalytic converter replaces the factory unit on 1997-2005 Pontiac Bonneville H-Body / G-Body models equipped with the 3.8L V6 engine to restore OBD-II emissions conversion and eliminate exhaust restriction.

The Stock Pontiac Bonneville Catalytic Converter Failure

Over high mileage on the H-Body / G-Body platform, severe thermal cycling and unburned fuel from aging ignition components cause the factory ceramic substrate inside the L36 / L67 3.8L V6 converter to fracture and melt. Once the precious-metal washcoat degrades or internal material breaks loose, exhaust flow stalls and downstream oxygen sensor readings mirror upstream data. This drop in oxygen storage capacity triggers persistent P0420 fault codes while creating excessive backpressure under load.

Common Symptoms of a Failing OEM Catalytic Converter

• Check Engine Light / DTCs: Illuminated MIL storing P0420 or P0430 catalyst efficiency below threshold codes in the PCM.
• Internal Substrate Rattle: Audible metallic rattling beneath the floorpan at idle or deceleration caused by a fractured ceramic core.
• Exhaust Backpressure & Emissions Failure: Sluggish throttle response, elevated underbody heat, and failed OBD-II readiness or emissions inspections.

The Direct-Fit Stainless Exhaust Solution

Engineered as a bolt-on OEM replacement, this converter pairs a corrosion-resistant stainless steel body (8 in length, 5 in height) with factory-positioned front flange and rear clamp geometry for zero cutting or welding. Inside, a ceramic honeycomb substrate treated with a precious-metal washcoat converts HC, CO, and NOx emissions to meet EPA Federal requirements. A precision-welded post-catalyst O2 sensor port ensures accurate downstream monitoring for leak-free OBD-II compliance.

What's Included

• 1 x Direct-Fit Catalytic Converter
• 1 x Front Flange Gasket
• 1 x Rear U-Bolt Clamp
• Mounting Bolts, Nuts, and Washers

Technical Specifications

Compatibility

• Make: Pontiac
• Model: Pontiac Bonneville 3.8L (SE, SLE, SSE, SSEi)
• Years: 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
• Engine: 3.8L V6 (Naturally Aspirated & Supercharged)

Frequently Asked Questions & Fitment Warnings

Does this fit the H-Body / G-Body Bonneville?

Yes. This is a direct fit for the 1997-2005 Pontiac Bonneville equipped with the L36 / L67 3.8L V6 engine, including the supercharged SSEi. Not compatible with 4.6L V8 GXP models. This EPA federal unit is not CARB approved and is not legal for vehicles registered in California, New York, Colorado, or Maine.

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

Yes, it restores catalyst efficiency when the factory converter has failed, though oxygen sensors are not included. Transfer your existing post-catalyst O2 sensor or install a new unit, and inspect for upstream exhaust leaks that can trigger false P0420/P0430 codes.

Are gaskets and mounting hardware included for installation?

Yes. The package includes the flange gasket, U-bolt clamp, and bolts, nuts, and washers; soak seized OEM fasteners with penetrating oil once the exhaust is cool and torque all joints evenly.

The Pontiac Precision Standard

Built to maintain strict OBD-II readiness and quiet underbody operation, this stainless converter restores factory exhaust flow across both naturally aspirated and supercharged 3800 drivetrains. Compare against your original unit prior to installation to confirm exact flange alignment and CEL-free emissions performance.