A-Premium Downstream Heated O2 Oxygen Sensor for Hyundai/Kia — 4-Wire B1S2, Threaded Direct Fit

The A-Premium downstream (B1S2) heated oxygen sensor replaces the rear O2 sensor on select Hyundai and Kia models to restore accurate exhaust monitoring and emissions performance.

This OEM-fit replacement oxygen sensor is engineered to match factory dimensions and electrical connections for a straightforward swap. It uses a 4-wire heated design and threaded mounting to provide fast warm-up and reliable feedback to the engine control module. Before ordering, verify vehicle compatibility with your year, engine size, drivetrain, and emissions configuration using the fitment details below.

Which vehicles and years does this downstream sensor fit?

This A-Premium sensor covers many Hyundai and Kia applications across several production years. Fitment is split by specific engine sizes and transmissions; some listings apply only to California or federal emissions versions, so double-check your VIN or vehicle selector.

• Hyundai Sonata: 2009–2015 variants with 2.4L engines (specific model years and transmission types apply).
• Hyundai Tucson/Santa Fe/Genesis Coupe and select Santa Fe Sport models across 2010–2016 ranges.
• Kia Forte, Forte Koup, Optima, Sorento, Sportage models with 2.0L or 2.4L engines for listed years.
• Not compatible with models requiring Federal emissions configuration on certain listings—confirm before purchasing.

What are the technical specifications and reference numbers?

This unit is a threaded, heated oxygen sensor with a male connector and four wires for heater and signal circuits. It ships boxed as a single sensor and is intended as a direct replacement for the factory downstream sensor.

• Sensor type: Heated downstream oxygen sensor (B1S2).
• Wire count: 4 (heater + signal/ground circuits).
• Mounting: Threaded for standard O2 bung installation.
• Reference numbers: 250-24878, 350-34630, 25024878, 35034630.

How do I confirm fitment and install the sensor?

Always enter your vehicle information in the selector or verify VIN compatibility before ordering. Installation typically requires access under the vehicle or to the exhaust pipe and basic hand tools; anti-seize and proper torque help ensure a reliable seal.

• Check vehicle year, engine displacement, transmission type, and emissions label.
• Unplug the factory harness, remove the old threaded sensor, apply anti-seize to new threads if needed, and torque to spec.
• Reconnect the 4-pin harness and clear any OBD-II codes after replacement.

What are the performance and quality considerations?

This aftermarket sensor is produced to meet common OEM electrical and physical standards for the listed applications. Using a heated sensor reduces warm-up time, helping the engine control module obtain meaningful oxygen readings sooner after start-up.

• Heated element for faster activation during cold starts.
• Male connector with factory-style wiring for plug-and-play replacement.
• Boxed single-piece packaging for protection in transit.

Who is this for: The A-Premium downstream O2 sensor is intended for DIY mechanics and professional technicians replacing a failing rear oxygen sensor on compatible Hyundai and Kia vehicles. If your vehicle shows downstream sensor fault codes, reduced fuel/diagnostic performance, or failed emissions checks and your model year/engine matches the listing, this direct-fit, 4-wire heated sensor provides a cost-effective replacement. Remember to confirm your vehicle details (VIN/year/engine/transmission/emissions) before purchase to ensure proper compatibility.