O2 Oxygen Sensor Upstream Downstream for GMC Yukon XL 1500 (2003-2005) 5.3L

Direct-Fit 4-Piece O2 Sensor Kit for 2003-2005 GMC Yukon XL 1500 (GMT800)

What it Does: This 4-piece upstream and downstream oxygen sensor kit monitors exhaust air-fuel ratios and catalyst efficiency on the 2003-2005 GMC Yukon XL 1500 GMT800 (LM7 / L59 5.3L).

The Stock GMC Yukon XL 1500 Sensor Failure

Factory narrowband zirconia sensors on the GMT800 endure extreme thermal cycling and exhaust condensate along the LM7 / L59 5.3L Y-pipe. Over time, ceramic elements fracture from heat soak, additives glaze platinum electrodes, and internal heaters burn out. Slowed switching strips the PCM of closed-loop fuel control, triggering P0135, P0141, P0155, and P0171/P0174 codes while hurting mileage.

Common Symptoms of a Failing OEM Sensor

• Check Engine Light: Faults like P0135, P0141, P0155 (heater), or P0133 (slow response).
• Rough Idle: Sluggish millivolt switching skews fuel trims and causes hesitation.
• Poor MPG: Open-loop enrichment increases fuel burn and blocks emissions readiness.

The Direct-Fit Oxygen Sensor Solution

Replacing all four sensors simultaneously with this matched 234-4668 kit restores synchronized Bank 1 and Bank 2 switching across upstream and downstream bungs. Each unit uses a laser-welded stainless shield, breathable PTFE filter, and zirconia thimble to resist moisture shock. Factory-spec 4-wire harnesses and OEM weatherpack connectors plug directly into the GMT800 chassis loom without cutting.

What's Included

• 2 Upstream Oxygen Sensors
• 2 Downstream Oxygen Sensors

Technical Specifications

Compatibility

• 2003-2005 GMC Yukon XL 1500 5.3L (2 Upstream, 2 Downstream)
• FIT FOR note: 2004-2005 Yukon, Tahoe, Silverado, Escalade 5.3L (confirm engine before ordering)
• Excludes: 2003-2006 Yukon XL 6.0L (Sheet 2828) and 2000-2002 / 2006 5.3L

Frequently Asked Questions & Fitment Warnings

Does this fit the GMT800 Yukon XL 1500?

Yes. Fits 2003-2005 GMC Yukon XL 1500 with the LM7 / L59 5.3L engine. Excludes 2003-2006 6.0L (Sheet 2828) and 2000-2002 or 2006 5.3L years.

Will this clear P0135, P0141, or P0155 codes?

Yes, if sensors caused the fault. Replacing all four resolves open heaters and slow switching; verify wiring and exhaust gaskets near the 234-4668 bungs.

Are connectors plug-and-play without splicing?

Yes. All four sensors include direct-fit OEM connectors; keep tips clean and torque to spec.

The GMC Heavy-Duty Standard

Engineered for sustained towing thermal loads on the GMT800 platform, this matched set maintains tight 5.3L closed-loop fueling and reliable emissions compliance.