O2 Oxygen Sensor Upstream Downstream for GMC Sierra 1500 (2014-2017) 4.3L, 5.3L, 6.2L

Direct-Fit 4-Piece Oxygen Sensor Kit for 2014-2017 GMC Sierra (K2XX)

What it Does: The complete 4-piece O2 sensor kit monitors pre- and post-catalytic exhaust gas concentrations on 2014-2017 GMC Sierra trucks to maintain accurate closed-loop air-fuel ratios and prevent emissions-related DTCs.

The Stock GMC Sierra Sensor Degradation

Factory oxygen sensors on the K2XX platform suffer from contamination and heater degradation over extended service intervals. Constant thermal cycling, sulfur deposits, and oil blow-by foul the porous ceramic thimble, causing sluggish switching speeds and inaccurate millivolt outputs. This degradation triggers intermittent P0135/P0161 heater circuit faults, excessive fuel consumption, erratic idle, and false P0420/P0430 catalytic converter inefficiency codes.

The Engineering Solution

This 4-sensor replacement set utilizes high-grade zirconium dioxide sensing elements matched to fast-acting planar heating circuits for rapid closed-loop activation. Featuring heavy-duty double-braided shielding and precision silicone seals, these sensors eliminate moisture intrusion and signal drift under severe exhaust heat. Direct-fit multi-pin harnesses plug straight into OEM harness clips without repinning, while factory-threaded M18 bung interfaces ensure leak-free seal integrity across both exhaust banks.

What's Included

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

Technical Specifications

Compatibility

• 2014-2017 GMC Sierra 1500 4.3L V6 EcoTec3 (LV3)
• 2014-2017 GMC Sierra 1500 5.3L V8 EcoTec3 (L83)
• 2014-2017 GMC Sierra 1500 6.2L V8 EcoTec3 (L86)

Frequently Asked Questions & Fitment Warnings

Does this fit the K2XX Sierra?

Yes, this is a direct fit for the 2014-2017 GMC Sierra equipped with the LV3, L83, or L86 engine. Verify current connector style and harness reach prior to installation.

Should I replace all four sensors at the same time?

Yes, replacing upstream and downstream units concurrently balances ECM switching cross-counts and eliminates bank-to-bank fuel trim disparities.

The GMC Towing Caliber

Full-size GM work trucks demand exact fuel trimming to preserve exhaust catalysts under heavy towing loads, keeping your drivetrain responsive and code-free on any worksite.