A-Premium Downstream O2 Oxygen Sensor for Toyota & Lexus — 4‑Wire Heated, Threaded Direct Fit

The A-Premium downstream (B1S2) heated oxygen sensor replaces the factory unit to restore accurate exhaust monitoring for compatible Toyota and Lexus models.

If your vehicle is showing an O2 sensor code, reduced fuel economy, or fluctuating emissions readiness, this direct-fit downstream oxygen sensor from A-Premium is built to match original equipment form, fit and function. It’s designed for threaded installation and comes with a four-wire heated connector to integrate with vehicles that require sensor heating and precise lambda feedback downstream of the catalytic converter.

Which Toyota and Lexus models is this oxygen sensor compatible with?

This downstream sensor covers a range of Toyota and Lexus applications across several model years. It fits vehicles with both 1.5L and 1.8L four-cylinder engines as well as select 3.5L V6 models when specified as the downstream/front location.

• Lexus CT200h: 2011–2017 L4 1.8L (B1S2 downstream)
• Toyota Prius & variants: Prius 2010–2015 L4 1.8L, Prius C 2012–2019 L4 1.5L, Prius V 2012–2017 L4 1.8L, Prius Plug-in 2012–2015 L4 1.8L
• Lexus RX350/RX450h and Toyota Highlander/Sienna: select 2011–2016 V6 3.5L applications (downstream/front positions per model notes)

What are the key specifications and electrical details?

This sensor uses a 4-wire heated design to speed warm-up and provide stable oxygen readings under a variety of exhaust temperatures. The product ships as a single boxed sensor with a male connector and threaded mounting to match OE replacement steps.

• Wire quantity: 4 (heated sensor)
• Overall cable length: 575 mm
• Mounting: threaded oxygen sensor bung
• Connector gender: male; package quantity: 1 sensor per box

How do I confirm fitment for my vehicle before ordering?

Always verify compatibility by entering your exact vehicle year, make, model, engine and position in the listing’s vehicle selector. Cross-reference the supplier reference numbers if you need to match part history or compare with your OEM sensor.

• Reference numbers listed: 250-24870, 350-34074, 234-4400, 2344400
• Use the vehicle info tool at the top-left of the product page to check fitment
• Read the Special Notes section for model-year or submodel exceptions before ordering

What can I expect during installation and early operation?

Installation follows the same steps as replacing a threaded downstream O2 sensor: disconnect the negative battery terminal, unplug the sensor connector, remove the old sensor with an oxygen-sensor socket, and install the new sensor with the correct torque. After installation, engine management systems may take a short drive cycle to clear stored codes and update readiness monitors.

• Requires standard oxygen sensor socket and torque wrench
• Allow a short drive cycle for ECM to recalibrate and reset emissions readiness
• Inspect connector and harness for corrosion or heat damage during replacement

Who is this for: Technicians, DIYers and fleet maintenance teams who need a reliable downstream heated O2 sensor for specified Toyota and Lexus models. If you require an OE-style threaded, 4-wire heated sensor with verified vehicle fitment and a one-year unlimited-mileage warranty from A-Premium, this part is intended for your application. Make sure to confirm your vehicle details and check the special fitment notes before purchase to ensure correct selection.