HQPASFY Oxygen O2 Sensor Kit Upstream & Downstream 234-5029/234-4238 (2Pc) Restores Fuel Efficiency & ECU Accuracy

HQPASFY 234-5029 and 234-4238 oxygen sensors are a matched upstream and downstream two-piece replacement set designed to restore accurate air-fuel sensing and engine monitoring on compatible Hyundai and KIA models.

This replacement sensor kit includes both the upstream (pre-catalytic) and downstream (post-catalytic) O2 sensors engineered to match OE fitment numbers 234-5029 and 234-4238. When an oxygen sensor begins to age or fails, it can trigger check-engine warnings, reduce fuel efficiency and upset engine drivability. The HQPASFY pair is intended to bring the exhaust measurement system back to factory-like operation when installed and configured correctly.

How will replacing both upstream and downstream sensors affect drivability?

Swapping both sensors at once helps the engine control unit receive accurate oxygen readings before and after the catalytic converter, which stabilizes fuel trims and ignition timing. That can reduce hesitation, rough idle and false error codes caused by mismatched sensor behavior.

• Restores accurate air/fuel ratio feedback to the ECU
• Helps eliminate intermittent rough idle and power loss
• Reduces repeated diagnostic trouble codes tied to O2 sensors

Which vehicles will these part numbers fit?

This HQPASFY set replaces factory part numbers like 39210-2G100 and 39210-2G200 and fits specific Hyundai and KIA engines across several model years. Confirm engine size and model year before ordering to ensure direct compatibility without modification.

• Hyundai: Tucson (2009–2015 depending on engine), Sonata 2.4L (2009–2011), Santa Fe 2.4L (2010–2015)
• KIA: Forte/Forte5/Forte Koup (2010–2013), Optima 2.4L (2011–2012), Rondo 2.4L (2009–2012)
• KIA Sorento and Sportage 2.4L coverage for 2011–2015 and 2011–2014 respectively

What should I know before installing these oxygen sensors?

Proper prep and installation maximize sensor function and prevent detection issues. Clean any carbon build-up at the sensor port, use an oxygen-sensor wrench to avoid damaging threads, and reset the vehicle ECU with an OBD tool after installation so the system can relearn the new sensor responses.

• Remove carbon deposits from the sensor mounting interface first
• Use a dedicated O2 sensor socket or wrench for correct torque
• Reset or clear ECU/OBD data after install so the vehicle recognizes sensors

How durable are these replacement sensors and what warranty is included?

HQPASFY supplies these sensors with a 24-month warranty that covers manufacturing defects under normal use. While oxygen sensors are designed to withstand exhaust conditions, lifespan depends on engine condition, fuel quality and driving environment; timely replacement reduces risk of catalytic damage or engine performance issues.

• 24-month warranty for manufacturing and workmanship issues
• Designed to meet OE-style fit and functional expectations
• Replacement recommended upon persistent OBD codes or poor fuel trim

Who is this for: Owners, independent mechanics and fleet technicians who need a reliable, matched upstream and downstream oxygen sensor pair for specified Hyundai and KIA models. Choose this HQPASFY kit when you want vehicle-specific fitment, clear OE replacement numbers, and step-by-step installation guidance to restore accurate exhaust sensing and smoother engine operation.