2x Oxygen Sensor for 2003-2006 Nissan 350Z 2003-2006 Infiniti G35 FX35 3.5L Downstream Left + Right

Vehicle Compatibility

• Nissan 350Z (2003–2006) – 3.5L V6

• Infiniti G35 (2003–2006) – 3.5L V6

• Infiniti FX35 (2003–2006) – 3.5L V6

Sensor Position:

• Downstream (Post-Catalytic)

• Left + Right / Bank 1 & Bank 2

⚠️ These are rear O₂ sensors only. Not for upstream (air-fuel ratio) positions.

What Downstream O₂ Sensors Actually Do (and Why They Matter)

Downstream sensors don’t adjust fuel trims—but they monitor catalytic converter efficiency. When they fail, you’ll see:

• P0420 / P0430 catalyst efficiency codes

• Random CEL resets that never stay gone

• Failed emissions or smog tests

• Incorrect readiness monitors

Replacing both sides ensures balanced readings and prevents the ECU from chasing bad data.

Sensor Design & Features

• OEM-style connector (plug-and-play)

• Pre-calibrated for factory ECU logic

• High-temp wiring and sensor housing

• Fast response for accurate catalyst monitoring

• No splicing or modification required

Built to work with stock exhaust and catalytic converters.

Benefits After Replacement

Once installed, you’ll notice:

• Check engine light stays off

• Proper emissions readiness

• Stable catalyst efficiency readings

• Smoother ECU operation

• No more “clear and pray” cycles

This is how you actually fix the problem—not mask it.

Installation Notes

• Direct bolt-in replacement

• Located after the catalytic converters

• Penetrating oil recommended on older exhausts

• Torque to factory specs

• Clear codes after installation

Pro tip: Replace both downstream sensors together—mixing old and new almost always triggers repeat codes.

Emissions & Reliability

Failing downstream sensors won’t usually affect drivability—but they will fail emissions and keep the CEL on permanently. Fresh sensors restore proper monitoring and keep your VQ-powered car inspection-ready.

Boring fix. Necessary result.

Why Buy from Pro Street Online

At Pro Street Online, we sell parts that solve the issue, not parts that “might help.” This Downstream O₂ Sensor Pair is a smart, cost-effective fix for common VQ35 CEL headaches—without dealer pricing or sketchy universal sensors.