O2 Oxygen Sensor Upstream Downstream for GMC Sierra 1500, Yukon (2003-2005) 4.8L

Direct-Fit Replacement Oxygen Sensor Set for 2003-2005 GMC Sierra 1500, Yukon (GMT800)

What it Does: The 4-piece Oxygen Sensor Set replaces worn factory sensors on the 2003-2005 GMC Sierra 1500 and Yukon to restore precise closed-loop air-fuel ratios, eliminate hesitation, and maximize fuel efficiency.

The Stock GMC Sierra 1500, Yukon Sensor Failure Modes

Factory exhaust sensors in the GMT800 chassis endure extreme thermal cycling, carbon blow-by, and environmental contamination. Over time, the internal zirconia sensing elements become poisoned by unburnt hydrocarbons and silicone blow-by, leading to sluggish voltage switching. This sensor lag forces the powertrain control module (PCM) into poor fuel trim calculations, resulting in rich-running conditions, fouled spark plugs, failed smog inspections, and persistent diagnostic trouble codes including P0130, P0161, P0420, and P0430.

The Engineering Solution

Engineered to original equipment tolerances, this comprehensive 4-sensor package restores both upstream mixture regulation and downstream catalyst monitoring. Built with laser-welded stainless steel bodies, porous ceramic diffusion barriers, and dual-layer protective shielding, these sensors resist thermal shock and mechanical vibration under heavy loads. Pre-calibrated factory pigtails and OE-spec weather-pack connectors ensure exact harness length routing away from blistering exhaust manifold heat without splicing or pin modifications.

What's Included

• 2 Upstream Oxygen Sensors
• 2 Downstream Oxygen Sensors

Technical Specifications

Compatibility

• 2003-2005 GMC Sierra 1500 4.8L V8
• 2003-2005 GMC Yukon 4.8L V8

Frequently Asked Questions & Fitment Warnings

Does this fit the GMT800 Sierra 1500, Yukon?

Yes, this is a direct fit for the 2003-2005 GMC Sierra 1500 and Yukon equipped with the 4.8L LR4 Vortec engine; always verify harness connector style before installing.

Should anti-seize compound be used during installation?

Apply anti-seize exclusively to the threaded housing while ensuring none contacts the active sensor element, and clear stored ECM codes after securing wiring harness clips.

The GMC Heavy-Duty Reliability Standard

Built for rigorous towing, heavy payload hauling, and everyday dependability, these sensors restore the rapid telemetry your truck needs to maintain safe exhaust gas temperatures and optimal towing performance.