A-Premium O2 Oxygen Sensor for Chevy GMC Buick Hummer – Downstream 4-Wire Heated, 400mm Lead

A-Premium's downstream heated 4-wire O2 oxygen sensor replaces your factory unit for compatible Chevy, GMC, Buick, Hummer and related models to restore accurate exhaust oxygen readings.

When your check engine light flags an O2 sensor or your vehicle shows reduced fuel efficiency and rough idle, this direct-fit downstream oxygen sensor is a common replacement choice. Built to match common OE specifications, the A-Premium sensor uses a threaded, heated sensing element with a 4-wire male connector and a 400 mm lead to plug into the factory harness without splicing. It’s sold individually in protective box packaging and comes with reference numbers often used to verify compatibility.

Which vehicles and engine types will this A-Premium oxygen sensor fit?

This downstream sensor is listed for many General Motors family vehicles and related models across 2007–2017 model years. It fits multiple engine displacements and both four- and six-cylinder applications, typically occupying Bank 1 Sensor 2 (B1S2) and in some models Bank 2 Sensor 2 (B2S2).

• Buick: Enclave 2008 3.6L, LaCrosse 2010 2.4L, Lucerne 2009–2011 3.9L, Rainier 2007 4.2L
• Chevrolet: Equinox/Malibu/Orlando/Captiva Sport/Colorado/Trailblazer 2007–2017 2.4L–4.2L
• GMC/Hummer/Pontiac/Saab/Saturn/Isuzu: Acadia/Canyon/Envoy/Terrain/H3/Outlook/9-7x/Aura/Vue/Solstice/Ascender/i-series
• Reference numbers: 12599204, 12604538, 12617907, 12597947, 12618010, 12618012, 250-24708

How does the sensor’s specification matter for fit and performance?

Spec details determine electrical compatibility, mounting method and wire routing. This A-Premium unit is a threaded, heated sensor with four wires and a 400 mm cable length — a common OE-style configuration that supports on-board diagnostics and rapid warm-up for accurate readings.

• Wire quantity: 4 — provides heater power plus signal/ground connections
• Overall length: 400 mm — suits factory harness routing in listed models
• Mounting type: threaded — installs into standard exhaust bung
• Connector gender: male — designed to mate with factory female harness

What should I expect during installation and troubleshooting?

Installation typically requires an oxygen sensor socket or a wrench and basic hand tools. Replace the sensor while the exhaust is cool or use proper safety gloves; avoid pulling or twisting the wiring harness. After installation, clear stored codes and run the vehicle to confirm the check engine light and any drivability issues are resolved.

• Tools: O2 sensor socket, ratchet, penetrating lubricant if sensor is seized
• Installation tip: ensure correct thread engagement and do not over-torque
• Post-install: clear ECU codes and perform a short drive cycle to verify operation
• Packaging: single sensor shipped in a protective box

Are there part numbers and compatibility checks I should confirm before buying?

Cross-referencing the listed reference numbers and checking bank/sensor position against your vehicle’s service information helps ensure a match. This A-Premium sensor lists multiple GM reference numbers used by dealers and aftermarket suppliers — use them together with year, make, model and engine size when ordering.

• Common references included: 12599204, 12604538, 12617907, 12597947
• Confirm bank position: B1S2 or B2S2 as required for your vehicle
• Compare connector style and wire count to the factory sensor
• Verify engine displacement and model year against fitment list

Who is this for: This A-Premium downstream heated oxygen sensor is intended for DIY mechanics, independent shops and fleet technicians replacing a failing or aged O2 sensor on compatible GM and related vehicles. It suits anyone who needs a direct-fit, 4-wire heated sensor with standard threaded mounting and factory-style connector for straightforward replacement.