Buy Nissan 350Z Oxygen Sensors

An oxygen sensor - also called an O₂ sensor, lambda sensor, or air-fuel-ratio sensor - threads into the Nissan 350Z's exhaust so it can compare oxygen in the hot exhaust to the air outside the pipe. That little reading tells the engine computer to add or pull back fuel, keeping the mix near the ideal 14.7-to-1 ratio for clean power and good mileage according to Wikipedia.
When the sensor works right, you get smoother driving, lower emissions, and up to double-digit fuel-economy gains; when it fails, the check-engine light glows and gas bills climb. Car and Driver notes that a bad sensor is one of the most common reasons that light comes on.

Inside the probe is a ceramic cell that generates a small voltage as oxygen levels change; the engine control unit (ECU) reads that voltage in Òclosed-loopÓ mode and fine-tunes fuel delivery many times a second. (Wikipedia, Wikipedia)
A healthy sensor helps the catalytic converter scrub toxins while saving fuel, but a worn unit skews the mix and can quickly over-heat or poison the converter. (Wikipedia)

The 350Z's VQ35DE/HR engines have four sensors: two ÒupstreamÓ (Bank 1 Sensor 1 on the passenger side front pipe; Bank 2 Sensor 1 on the driver side front pipe) and two ÒdownstreamÓ just after each main catalytic converter (Bank 1 Sensor 2, Bank 2 Sensor 2). Community technicians confirm that Bank 1 equals the passenger side on U.S. models. (My350Z)

• Upstream sensors (sometimes called ÒfrontÓ or Òpre-catÓ) do the heavy lifting of fuel-trim control.
• Downstream sensors (ÒrearÓ or Òpost-catÓ) mostly verify that each catalytic converter is working; they do not normally adjust fuel. (My350Z)

Common hints that a 350Z lambda probe is failing include:

• Check-engine light with codes such as P0130-P0141, P0161.
• Rough idle or stalling.
• Flat-feeling throttle and sluggish acceleration.
• Drop in miles-per-gallon (MPG).
• Failed emissions test.

These symptoms line up with the eight-item checklist from Mechanic Base.

Heated O₂ sensors on most modern cars last about 100,000 miles; unheated units last roughly half that. (Wikipedia)
Nissan's factory service manual advises letting the exhaust cool to avoid stripped threads and burns. (NICOclub)
When threading in a new unit, tighten to 45 Nám / 33 lb-ft on the 350Z's stainless bung. (350z-tech.com)
A dedicated 22 mm (7Ú8-in.) oxygen-sensor socket makes the job easier in tight spaces.

• 22 mm offset oxygen-sensor wrench or crow-foot socket.
• Anti-seize on the threads (avoid the first two threads near the tip).
• Torque wrench set to 33 lb-ft.

Replacing a lazy air-fuel sensor can bump fuel economy by up to 15 percent, according to a 2025 fleet-efficiency study. (fleetrabbit.com)
The U.S. EPA adds that fixing emissions-related problems such as a bad O₂ sensor often saves 6 - 13 percent in fuel. (EPA NEPIS)
Drivers on automotive Q&A sites report real-world MPG jumps after swapping a clogged sensor. (Mekanik Otomotif Stack Exchange)

A glitchy probe can increase smog-forming NOx and hydrocarbon output several-fold, says an EPA field study on sensor durability. (EPA NEPIS)
Because the downstream unit monitors catalytic-converter efficiency, a Òbad catÓ code often traces back to the sensor itself. (My350Z)
EPA guidance warns that tampering with lambda signals is illegal and harms air quality. (US EPA)

Bosch introduced the first planar O₂ sensor to mass production in 1994, shrinking warm-up times and boosting accuracy. (assets.bosch.com)
Wide-band sensors (often called UEGO sensors) read a broad mixture range and help tuners dial in performance, as noted by Wikipedia.

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Codes above appear frequently on 350Z forums and in OBD-II reference charts. (Mechanic Base, My350Z)

The Nissan 350Z oxygen sensor is a small but vital runner in the engine-emissions relay. Keep it healthy, tighten it to spec, and replace it every 100 k miles or when codes pop up. You'll enjoy crisper throttle, cleaner air, and money back in your pocket at every fuel stop.