O2 Oxygen Sensor Upstream Downstream for GMC Yukon (2015-2018) 5.3L, 6.2L

Direct-Fit Complete Upstream and Downstream O2 Sensor Kit for 2015-2018 GMC Yukon (K2XX)

What it Does: The 4-piece oxygen sensor kit monitors pre- and post-catalytic exhaust gas oxygen concentrations on the 2015-2018 GMC Yukon to optimize closed-loop fuel trim mapping and preserve catalytic converter efficiency.

The Stock GMC Yukon Sensor Degradation

Factory oxygen sensors on the K2XX platform endure extreme thermal cycling, carbon deposits, and oil vapor contamination common to high-mileage EcoTec3 L83 / L86 direct-injection engines. Over time, OEM zirconia elements lose response speed, causing sluggish switching ratios between rich and lean states. This slow signal feedback degrades short-term fuel trim (STFT) accuracy, delays closed-loop engine management, triggers P0135/P0141 heater circuit trouble codes, and leads to unburned hydrocarbon accumulation that rapidly degrades catalytic substrates.

The Engineering Solution

This 4-sensor replacement kit features high-temperature planar ceramic sensing elements engineered for rapid light-off times and precise lambda detection. Enclosed in double-laser-welded stainless steel bodies, each sensor resists vibration, thermal shock, and silicone poisoning. Factory-correct wiring harnesses, pre-pinned weather-pack terminal connectors, and OE-matched lead lengths ensure direct plug-and-play installation without cutting or splicing, restoring stoichiometric 14.7:1 air-fuel ratios, cold-start efficiency, and steady idle stability across both banks.

What's Included

• 2 x 234-4940 Upstream Oxygen Sensors
• 2 x 234-4974 Downstream Oxygen Sensors

Technical Specifications

Compatibility

• 2015-2018 GMC Yukon 5.3L V8 (EcoTec3 L83)
• 2015-2018 GMC Yukon 6.2L V8 (EcoTec3 L86)
• 2015-2018 GMC Yukon XL 5.3L V8 (EcoTec3 L83)
• 2015-2018 GMC Yukon XL 6.2L V8 (EcoTec3 L86)

Frequently Asked Questions & Fitment Warnings

Does this fit the K2XX Yukon?

Yes, this is a direct fit for the 2015-2018 GMC Yukon equipped with the 5.3L L83 or 6.2L L86 EcoTec3 engine. Verify harness pin count and engine displacement prior to installation.

Should these sensors be replaced individually or as a complete axle/engine set?

Replacing upstream and downstream sensors simultaneously across Bank 1 and Bank 2 prevents false delta readings between pre- and post-catalyst feedback loops.

The GMC Heavy-Duty Reliability Standard

Full-size truck and SUV platforms operating under heavy towing loads demand precise AFR calibration; these direct-fit sensors maintain exhaust monitoring integrity under sustained high-exhaust-gas temperatures (EGTs) without dropping communication with the ECM.