O2 Oxygen Sensor Upstream Downstream for GMC Sierra 2500 HD 3500 HD (2003-2007) 6.0L

Direct-Fit Upstream & Downstream Oxygen Sensor Kit for 2003-2007 GMC Sierra (GMT800)

What it Does: The direct-fit oxygen sensor kit replaces degraded factory upstream and downstream O2 sensors on 2003-2007 GMC Sierra HD trucks to restore stoichiometric air-fuel feedback and resolve sluggish sensor DTCs.

The Stock GMC Sierra Sensor Degradation

Factory sensors on high-mileage GMT800 platforms routinely suffer from exhaust soot fouling, oil-vapor contamination, and severe thermal fatigue. Over time, the internal zirconia ceramic sensing element loses rapid millivolt switching response between lean and rich fuel states. Additionally, open circuits within the internal heater elements trigger diagnostic trouble codes such as P0135, P0141, P0155, or P0161. When this occurs, the powertrain control module cannot maintain closed-loop operation on the LQ4 engine, forcing a fixed rich condition that wastes fuel, compromises towing power, and overheats catalytic converters.

The Engineering Solution

Engineered to OEM operating parameters, these upstream and downstream oxygen sensors utilize precision planar ceramic sensing cores shielded by high-grade 300-series stainless steel dual-protection outer shells. High-output integrated ceramic heating circuits reach operating light-off temperatures within seconds to rapidly transition the ECU into closed-loop monitoring. Each sensor features factory-pinned connectors, corrosion-resistant wiring leads, and pre-coated anti-seize threads to match OEM interchange part numbers including 213-4229, 234-4254, and 234-4407.

What's Included

• 2x Upstream Oxygen Sensors
• 2x Downstream Oxygen Sensors

Technical Specifications

Compatibility

• 2003-2007 GMC Sierra 2500 HD 6.0L V8
• 2003-2007 GMC Sierra 3500 HD 6.0L V8

Frequently Asked Questions & Fitment Warnings

Does this fit the GMT800 Sierra?

Yes, this is a direct fit for the 2003-2007 GMC Sierra 2500 HD and 3500 HD equipped with the LQ4 6.0L engine. Confirm your vehicle is equipped with the 6.0L V8 gasoline engine before ordering; 6.6L Duramax and 8.1L platforms are excluded.

Do I need to reset fuel trims after installing these sensors?

Yes, clearing active DTCs and executing a PCM fuel trim reset with an OBD-II scanner allows the engine to immediately relearn accurate closed-loop fuel maps.

The GMC Heavy-Duty Caliber

Engineered to handle severe towing loads and high-exhaust-temperature duty cycles, this matched oxygen sensor set maintains precise air-to-fuel calibration to keep heavy-duty Sierra trucks operating cleanly and reliably under payload.