O2 Oxygen Sensor Upstream Downstream for Ford Expedition (1997-2008) 4.6L, 5.4L

Direct-Fit O2 Oxygen Sensor Upstream and Downstream Set for 1997-2008 Ford Expedition (UN93 / U222 / U324)

What it Does: The O2 Oxygen Sensor Upstream and Downstream Set monitors exhaust gas oxygen concentration on the 1997-2008 Ford Expedition to optimize air-fuel mixture control and ensure catalytic converter efficiency.

The Stock Ford Expedition Oxygen Sensor Degradation

Over prolonged duty cycles, factory oxygen sensors on the UN93, U222, and U324 platforms suffer from silica contamination, fuel additive glazing, and thermal fatigue. As the internal zirconia electrolytic core and platinum electrodes foul from exhaust blow-by, reaction times slow down dramatically. This sensor lag skews short-term and long-term fuel trims, forcing the Ford Modular V8 PCM into rich-running defensive maps. Symptoms include degraded fuel economy, rough idle, hesitation under load, and diagnostic trouble codes including P0130, P0161, P0420, and P0430.

The Engineering Solution

This 4-piece replacement set delivers precise closed-loop stoic feedback via high-grade ceramic sensing elements protected by double-laser-welded stainless steel housings. Manufactured to match exact OEM harness lengths, wire gauges, and weather-pack pinouts, each sensor threads directly into standard M18x1.5 factory exhaust bungs without wire splicing or pin repinning. Replacing both bank 1 and bank 2 upstream regulation sensors alongside post-cat monitoring sensors restores factory baseline lambda response, stabilizes combustion stoichiometry, and clears catalyst-efficiency check engine lights.

What's Included

• 2 Upstream Oxygen Sensors
• 2 Downstream Oxygen Sensors

Technical Specifications

Compatibility

• 1997-2008 Ford Expedition 4.6L V8
• 1997-2008 Ford Expedition 5.4L V8

Frequently Asked Questions & Fitment Warnings

Does this fit the UN93 / U222 / U324 Expedition?

Yes, this is a direct fit for the 1997-2008 Ford Expedition equipped with the Ford Modular V8 4.6L and 5.4L engines across all generation chassis. Always verify connector keying and harness lengths prior to installation.

What precautions should be taken when installing these oxygen sensors?

Use a designated slotted oxygen sensor socket, apply high-temperature anti-seize exclusively to the external threads while keeping the porous sensor tip completely clean, and route harness wiring safely away from direct exhaust runner heat.

The Ford Heavy-Duty Standard

Full-size truck chassis and heavy-duty towing applications place intense thermal demands on exhaust monitoring components; these direct-replacement sensors ensure balanced combustion, maximum pulling efficiency, and extended catalytic converter life under heavy payload conditions.