Catalytic Converter for GMC Sierra (2014-2018) 4.3L 5.3L

Direct-Fit Stainless Catalytic Converter Pair for 2014-2018 GMC Sierra (K2XX)

What it Does: This direct-fit catalytic converter pair replaces both factory exhaust banks on the 2014-2018 GMC Sierra 1500 (K2XX) equipped with the LV3 4.3L V6 or L83 5.3L V8 to restore emissions compliance and exhaust flow.

The Stock GMC Sierra Catalytic Converter Failure

Factory catalytic converters on the K2XX Sierra 1500 endure extreme thermal cycling under towing and heavy-load operation with the LV3 4.3L V6 and L83 5.3L V8 engines. Over time, repeated heat soak and minor fuel trim imbalances fracture the internal ceramic brick and degrade the precious-metal washcoat. Once the substrate breaks loose inside the shell, it restricts exhaust scavenging, triggers catalyst-efficiency faults like P0420 and P0430, and creates an audible metallic rattle under deceleration.

Common Symptoms of a Failing OEM Catalytic Converter

• Check Engine Light / Catalyst DTCs: Stored P0420 (Bank 1) or P0430 (Bank 2) codes caused by depleted oxygen storage capacity across the catalyst bed.
• Metallic Exhaust Rattle: Audible rattling beneath the cab at idle or low RPM due to a fractured ceramic substrate vibrating inside the converter housing.
• Sluggish Acceleration & Failed Emissions: Elevated exhaust backpressure choking top-end power and high HC, CO, and NOx tailpipe readings during federal OBD-II inspection.

The Direct-Fit Stainless Exhaust Solution

This complete left-bank Y-pipe and right-bank converter assembly restores factory exhaust flow across both cylinder banks simultaneously. Built with corrosion-resistant stainless steel tubing and an 8-inch by 5-inch converter body, each pipe resists thermal cracking and road-salt oxidation. Inside, a high-flow ceramic honeycomb substrate coated in precious-metal washcoat maintains proper light-off temperatures for HC, CO, and NOx conversion. Factory-style manifold flanges, integrated O2 sensor ports, and exact-match pipe bends bolt directly into the OEM exhaust system without cutting or welding.

What's Included

• 1 x Left Y-Pipe Catalytic Converter Assembly
• 1 x Right Catalytic Converter Pipe
• 1 x U-Clamp
• 6 x Bolts with Nuts and Washers

Technical Specifications

Compatibility

• 2014-2018 GMC Sierra 1500 Base (4.3L V6)
• 2014-2018 GMC Sierra 1500 SLE (4.3L V6)
• 2014-2018 GMC Sierra 1500 Base (5.3L V8)
• 2014-2018 GMC Sierra 1500 SLE (5.3L V8)
• 2014-2018 GMC Sierra 1500 SLT (5.3L V8)
• 2014-2018 GMC Sierra 1500 Denali (5.3L V8)
• Exclusions: Not compatible with 6.0L or 6.2L engines, 2019 and newer models, or vehicles registered in CA, NY, CO, or ME.

Frequently Asked Questions & Fitment Warnings

Does this fit the K2XX Sierra?

Yes. This is a direct fit for the 2014-2018 GMC Sierra 1500 equipped with the LV3 4.3L V6 or L83 5.3L V8 engine. It does not fit 6.0L or 6.2L engines, 2019 and newer trucks, and is not CARB approved for vehicles registered in California, New York, Colorado, or Maine.

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

Yes, it resolves catalyst-efficiency codes caused by a failed converter, though O2 sensors are not included. Transfer your existing sensors or install new ones into the integrated ports, and always inspect upstream exhaust joints for leaks that can falsely trigger P0420 or P0430.

What hardware is included, and what prep is needed for installation?

A U-clamp and six bolts with nuts and washers are included for mounting. Allow the exhaust to cool completely, soak seized manifold fasteners with penetrating oil, install using new gaskets, and torque all flange hardware evenly before checking every joint for leaks.

The GMC Heavy-Duty Standard

Built to withstand the sustained exhaust gas temperatures of towing, hauling, and daily work duties on the K2XX platform without substrate breakdown. Replacing both banks simultaneously ensures balanced exhaust backpressure and reliable long-term thermal durability.