O2 Oxygen Sensor Upstream Downstream for Mitsubishi Eclipse (2006-2012) 3.8L

Direct-Fit Upstream & Downstream O2 Oxygen Sensor Kit for 2006-2012 Mitsubishi Eclipse (DK4A)

What it Does: This 4-piece upstream and downstream oxygen sensor kit monitors pre- and post-catalyst exhaust oxygen content on the 2006-2012 Mitsubishi Eclipse DK4A equipped with the 6G75 3.8L V6 to maintain closed-loop air-fuel ratio accuracy and catalytic converter efficiency.

The Stock Mitsubishi Eclipse Oxygen Sensor Failure

On the DK4A chassis powered by the 6G75 3.8L V6, factory zirconia oxygen sensors endure continuous thermal cycling, exhaust soot, and moisture condensation. Over time, internal heater elements burn out and platinum electrodes suffer silicone or oil fouling, slowing voltage switching speed. When Bank 1 or Bank 2 upstream sensors lag, the ECU defaults to rich open-loop fuel maps, while degraded downstream sensors trigger catalyst efficiency faults like P0420/P0430 or heater circuit codes P0135 and P0155.

Common Symptoms of a Failing OEM Oxygen Sensor

• Check Engine Light / DTCs: Triggers slow-response, heater circuit, or catalyst codes such as P0134, P0154, P0135, P0155, and P0420/P0430 due to degraded voltage switching.
• Erratic Fuel Trims & Hesitation: Sluggish upstream feedback forces excessive short-term and long-term fuel trim corrections, causing rough idle and bogging under load.
• Failed Emissions & Fuel Waste: Prolonged open-loop enrichment spikes tailpipe hydrocarbons, accelerates catalytic converter overheating, and reduces fuel economy.

The Direct-Fit Upstream & Downstream Oxygen Sensor Solution

Replacing all four sensors simultaneously as a matched set restores balanced Bank 1 and Bank 2 feedback across both cylinder heads. These direct-fit heated zirconia sensors feature laser-welded stainless steel housings, dual-layer porous PTFE protective filters against exhaust contaminants, and precision-wound internal heaters for rapid light-off. Built with factory-length leads and weather-sealed OEM-style connectors, each sensor replaces 234-4318, 234-4656, 234-4738, and 234-4739 with zero wire splicing.

What's Included

• 2 Upstream Oxygen Sensors (Bank 1 & Bank 2)
• 2 Downstream Oxygen Sensors (Bank 1 & Bank 2)

Technical Specifications

Compatibility

• 2006-2012 Mitsubishi Eclipse 3.8L V6 (including 2011; 4-sensor setup: 2 upstream, 2 downstream)

Frequently Asked Questions & Fitment Warnings

Does this fit the DK4A Eclipse?

Yes. This is a direct fit for the 2006-2012 Mitsubishi Eclipse equipped with the 6G75 3.8L V6 engine, including the 2011 model year. Excludes 2.4L 4-cylinder Eclipse models and Mitsubishi Galant applications; always confirm your 3.8L V6 engine before ordering.

Will replacing all four sensors clear P0135, P0155, or P0420/P0430 codes?

Yes, when the fault stems from degraded oxygen sensors. Installing this matched kit resolves heater circuit and slow-response DTCs like P0135 and P0155, though persistent P0420/P0430 codes after replacement indicate an internally damaged catalytic converter substrate.

Do these sensors require wire splicing or special connectors for installation?

No. Each sensor arrives with direct-fit OEM-style plug-and-play connectors and factory-cut threads, requiring only a standard 22mm (7/8-inch) oxygen sensor socket and proper torque during installation.

The Mitsubishi Precision Standard

Engineered for the 6G75 V6 platform, this matched four-sensor kit restores crisp throttle response, balanced exhaust flow monitoring, and closed-loop fuel efficiency. Keep your Eclipse running clean and CEL-free with factory-grade ECU signal accuracy.