O2 Oxygen Sensor Upstream Downstream for Lincoln MKS MKT MKZ (2013-2016) 3.7L

Direct-Fit Upstream & Downstream O2 Sensor Kit for 2013-2016 Lincoln MKS, MKT, MKZ (D3/D4/CD4)

What it Does: This 4-piece oxygen sensor kit monitors exhaust oxygen on 2013-2016 Lincoln MKS, MKT, and MKZ 3.7L Ti-VCT V6 models to restore closed-loop fuel trim.

The Stock Lincoln MKS, MKT, MKZ Sensor Failure

Factory oxygen sensors on the D3 MKS, D4 MKT, and CD4 MKZ with the Duratec 37 3.7L Ti-VCT V6 endure severe, continuous exhaust heat cycling. Over time, internal heater coils suffer thermal fatigue while carbon and ash deposits poison the porous zirconia sensing core. This slows voltage switching and skews fuel trims, triggering P0135, P0155, or P0420/P0430 fault codes.

Common Symptoms of a Failing OEM Oxygen Sensor

• Check Engine Light: Triggers heater or slow-response codes like P0130, P0135, P0155, or P0420/P0430.
• Sluggish Response: Contaminated zirconia elements delay voltage switching, causing rough idle and erratic fuel trims.
• Poor Fuel Economy: Forces rich open-loop fueling, lowering mileage and failing emissions tests.

The Direct-Fit Matched Oxygen Sensor Solution

This matched 4-piece kit replaces OEM part numbers 234-5038 and 234-4490 across both exhaust banks simultaneously. Each sensor pairs a laser-welded stainless steel shell with a high-purity ceramic zirconia element and calibrated heater circuit for fast light-off and accurate voltage feedback. Direct-fit weather-pack connectors, OE harness lengths, and pre-coated threads bolt directly into stock bungs without wiring splicing.

What's Included

• 2 Upstream Oxygen Sensors (234-5038)
• 2 Downstream Oxygen Sensors (234-4490)

Technical Specifications

Compatibility

• 2013-2016 Lincoln MKS (D3) 3.7L
• 2013-2016 Lincoln MKT (D4) 3.7L
• 2013-2016 Lincoln MKZ (CD4) 3.7L

Frequently Asked Questions

Does this fit the D3, D4, and CD4 MKS, MKT, MKZ?

Yes. Fits 2013-2016 Lincoln MKS (D3), MKT (D4), and MKZ (CD4) 3.7L Ti-VCT V6 models. Excludes 2.0L, 3.5L EcoBoost, and hybrid engines; confirm engine before ordering.

Will this fix P0135, P0155, or P0420/P0430 codes?

Yes, if caused by sensor failure. New 234-5038 upstream and 234-4490 downstream sensors restore heater resistance and voltage waveforms when catalytic converters are intact.

Is wiring splicing required for installation?

No. All four sensors feature direct-fit factory connectors and pre-coated threads for plug-and-play installation.

The Lincoln Precision Standard

Built for factory PCM calibration, this matched 4-sensor kit restores closed-loop fuel accuracy and CEL-free operation on your 3.7L Ti-VCT V6.