OE-spec wideband oxygen sensor for stable fuel mix and clean exhaust

This upstream air‑fuel ratio sensor keeps the engine in perfect balance. It tells the ECU how rich or lean the burn is, so the system trims fuel for smooth power, low emissions, and great mpg. If you want steady idle, strong response, and a protected catalytic converter, this is the key piece.

Why you need it

Modern engines rely on precise feedback to hit the target lambda. A healthy sensor means quick closed‑loop control, easier cold starts, and fewer trips to the pump. It also helps your car pass inspections and keeps the cat from overheating.

How it works

Inside is a heated zirconia cell (wideband design). The ECU drives a tiny pump current through the cell; that current changes with oxygen content in the exhaust. The module reads it as lambda and adjusts injector pulse in real time. The heater brings the element to temp fast for accurate data.

What happens if it’s bad ⚠️

Check Engine Light, rough idle, flat spots, poor fuel economy, fuel smell, or failed emissions. Running rich can cook the catalyst; running lean can cause misfire and heat stress. Long-term, it costs more fuel and parts.

Install notes ✅

Fits the upstream (pre‑cat) position. Direct‑fit connector. Apply O2‑sensor‑safe anti‑seize to threads, torque to spec, route the harness away from heat, then clear codes and reset fuel trims.

• Harrier
• Harrier/Hybrid
• Highlander