234-5029 234-4238 Upstream Downstream O2 Oxygen Sensor Set of 2

Our review of the NECATUO 234-5029 234-4238 oxygen sensor set finds it best suited for DIY mechanics and independent shops who need a direct-fit replacement for Hyundai and Kia models. The bottom line: this set delivers OEM-style fit and straightforward installation for upstream and downstream positions, improving fuel trims and emissions monitoring when the original sensors wear out. It is primarily valuable for owners of 2.0L and 2.4L engines who want a cost-effective pair that matches the factory reference numbers and fitment list.

Key Features

• Vehicle Fitment: Covers a wide list of Hyundai and Kia models, making it easy to replace both upstream and downstream sensors on compatible 2.0L and 2.4L engines.
• Reference Numbers: Matches multiple OE and part numbers so installers can cross-reference for accurate replacement without guessing.
• OEM Quality: Constructed from premium materials designed to provide durable sensing and to help protect the catalytic converter over time.
• Easy Installation: Manufactured to OE specifications for fit, form, and function which reduces installation time for a direct swap in supported vehicles.
• Set Includes Two Sensors: Ships with one upstream and one downstream sensor so both critical positions are serviced at once for balanced performance.

Who It's For

This sensor set is ideal for owners of Hyundai Santa Fe, Sonata, Tucson and Kia Forte, Optima, Sorento, Rondo or Sportage model years listed in the fitment who want a like-for-like replacement without visiting a dealer. Mechanics who prefer to replace both sensors as preventive maintenance rather than only the failed unit will find the paired set practical and cost effective.

It is not the best choice for vehicles outside the stated fitment or for buyers seeking long-term performance data beyond initial fit and function. If a sensor is needed for a different engine variant or an uncommon model year, confirm compatibility using the listed reference numbers before purchase.

Pros & Cons

Pros

• Direct-fit replacement for many Hyundai and Kia 2.0L/2.4L engines, reducing installation complexity.
• Includes both upstream and downstream sensors so oxygen sensing and catalytic performance can be addressed together.
• Built to OEM specifications, which helps restore proper fuel economy and emissions control when installed correctly.

Cons

• Some customers reported an early failure in rare cases, so longevity may vary by vehicle condition and installation environment.

Specifications

Brand	NECATUO
Part Numbers	234-5029, 234-4238, 3921022620 and related OE numbers
Included Items	1 x 234-5029 upstream, 1 x 234-4238 downstream
Compatible Engines	2.0L and 2.4L engines (models listed)
Vehicle Coverage	Hyundai Santa Fe/Sonata/Tucson and Kia Forte/Forte5/Optima/Rondo/Sorento/Sportage
Quality	OEM-quality materials for durability

Our Verdict

The NECATUO 234-5029 234-4238 oxygen sensor set is a practical, value-oriented replacement for owners of compatible Hyundai and Kia vehicles who want a direct-fit upstream and downstream pair. It restores proper oxygen sensing and is built to OE specifications, making it a sensible buy for routine replacement or when addressing emissions and fuel trim symptoms, although buyers should be aware that isolated early failures have been reported.

Frequently Asked Questions

Will this set fit my Sonata or Santa Fe?
Check the listed years and engine sizes in the product fitment; it covers many 2.4L Sonata and 2.4L Santa Fe model years.

Does the set include both sensors needed?
Yes, the package includes one upstream (234-5029) and one downstream (234-4238) sensor for a complete replacement.

Are these sensors OEM quality?
They are manufactured to OE specifications and use premium materials intended to match factory fit and function.