O2 Oxygen Sensor Upstream Downstream for GMC Sierra (2008-2013) 4.3L

Direct-Fit O2 Oxygen Sensor Kit for 2008-2013 GMC Sierra (GMT900)

What it Does: This upstream and downstream O2 sensor kit monitors exhaust oxygen levels on the 2008-2013 GMC Sierra (GMT900) LU3 4.3L V6 for ECM fuel trim control.

The Stock GMC Sierra Oxygen Sensor Failure

On high-mileage GMT900 trucks with the LU3 4.3L V6, OEM oxygen sensors suffer from thermal cycling fatigue, carbon fouling, and heater circuit degradation. As the zirconia element ages, voltage switching slows and skews closed-loop fuel trim toward rich or lean drift. Exhaust heat soak and moisture intrusion also fracture internal heaters, triggering P0135, P0141, P0155, and P0161 alongside sluggish response codes like P0133 or P0171/P0174.

Common Symptoms of a Failing OEM Oxygen Sensor

• Check Engine Light / DTCs: Triggers P0135, P0141, P0171/P0174, or false P0420 codes from slow switching.
• Rough Idle & Hesitation: Delayed millivolt feedback disrupts closed-loop fueling under light load.
• Poor MPG & Emissions Failure: Rich open-loop defaulting increases fuel use and fails readiness tests.

The Direct-Fit Heated Zirconia Solution

Engineered to match OEM numbers 234-4337 and 234-4258, this 4-sensor kit restores crisp closed-loop feedback across both upstream and downstream banks. Each unit pairs a fast-acting heated zirconia element with a corrosion-resistant stainless steel housing built for extreme exhaust heat cycles. Factory-style weatherproof connectors and OEM-spec threads provide plug-and-play installation with zero wire splicing or harness modification.

What's Included

• 2 Upstream Oxygen Sensors
• 2 Downstream Oxygen Sensors

Technical Specifications

Compatibility

• 2008-2013 GMC Sierra 1500 (4.3L V6 Only)

Frequently Asked Questions & Fitment Warnings

Does this fit the GMT900 Sierra?

Yes. Fits 2008-2013 GMC Sierra 1500 with the LU3 4.3L V6. Excludes 4.8L, 5.3L, 6.0L, and 6.2L V8 engines; confirm engine before ordering.

Will this clear O2 heater and fuel trim codes?

Yes. Replacing all four sensors restores heater resistance and switching speed, clearing sensor-related P0135, P0141, and P0171/P0174 codes after ECM reset.

Is wire splicing required for installation?

No. Each sensor includes direct-fit factory plugs for bolt-in installation; verify exhaust flanges are leak-free before clearing codes.

The GMC Heavy-Duty Standard

Built for the thermal loads of daily hauling on the GMT900 platform, this matched sensor kit keeps your LU3 4.3L V6 operating at peak combustion efficiency and emissions readiness.