Is this an upstream or downstream sensor?

It is a downstream sensor, mounted after the catalytic converter. It is not the pre-cat sensor.

Does it need splicing or an adapter?

No. It is a direct-fit sensor with a factory-style male connector and a four-wire harness, so it plugs in as the original did.

Yes. The sensor is heated, which brings it up to operating temperature faster after a cold start.

What thread size does it use?

It has a threaded mount with a 0.708 in thread diameter, matching the standard O2 sensor bung.

One DENSO 234-4370 oxygen sensor. No sensor socket or other tools are included.

Fit depends on the vehicle. Check that your car's application calls for DENSO part number 234-4370 before ordering.

Where is the DENSO 234-4370 Oxygen Sensor cheapest?

At Walmart, for $47.22, 31% under what the other stores charge, as of our latest check.

What do buyers say about the DENSO 234-4370 Oxygen Sensor?

Rated 5 out of 5 from 1 ratings. Buyers like: Fast shipping and exactly what was ordered; Easy to find the part; price beat the dealer; Great customer service with fitment questions.

Where can I buy the DENSO 234-4370 Oxygen Sensor?

17 stores we checked sell it, including Team Vehicle, UpStart Auto Parts & More, Auto Parts and Stuff, Walmart, Newparts.com.

DENSO 234-4370 Oxygen Sensor Price History: $47.22 at Walmart

What reviewers say

Buyers who installed this sensor report it fit like the original part and resolved their check-engine codes.

What people mention

FitPraisedBuyers say it fit like the original part with no adapter or splicing needed.
ValueMixedSome buyers note it costs more than a generic universal sensor, though they call it honest pricing against the dealer.
PackagingPraisedBuyers report the sensor arrived well packaged and undamaged.

From UpStart Auto Parts & More

Oxygen sensor used for monitoring exhaust gas levels
Manufacturer: DENSO
Part Number: 234-4370
UPC: 042511114098
Sold in QTY: 1
Condition: New

Returns: Most items can be returned within 30 days of delivery if unused and in original, undamaged packaging; email for return instructions first; 15% restocking fee un
Shipping: Most orders ship from the warehouse the next business day unless otherwise noted; free shipping to the lower 48 (AK and HI excluded) via saver rate, arriving in
Packs: Quantity discounts: 2–9 save 2% each, 10–24 save 8% each, 25+ save 11% each.
In the box: DENSO 234-4370 Oxygen Sensor (QTY: 1)

About the DENSO 234-4370 Oxygen Sensor

The DENSO 234-4370 is a heated oxygen sensor that monitors exhaust gas levels. It is a direct-fit, vehicle-specific replacement, built to OE standards and tested. It installs downstream, in the catalyst.

It has an aluminum oxide trap layer that protects the ceramic element from silicone and lead poisoning. The design aims to support engine performance, fuel efficiency and long service life.