O2 Oxygen Sensor Upstream For Subaru Honda (2001-2006)

Optimizing Air-Fuel Management for the EJ25 and D17 Platforms

Who It’s For: Engineered for owners of the Subaru EJ25 (SOHC) and Honda D17-series engines who are seeing a dip in fuel economy or a sluggish mid-range response. Whether you are daily driving a Forester or maintaining a Civic EX, your engine’s ability to "breathe" efficiently depends entirely on the accuracy of its feedback loop.

The Symptom: The factory sensors on the 2.5L Boxer and 1.7L VTEC engines eventually become "lazy" due to carbon buildup and heat cycling. When the sensor fails to report accurate oxygen levels in the exhaust stream, the ECU defaults to a rich "fail-safe" map. This results in fouled spark plugs, a heavy smell of unburnt fuel, and a noticeable loss of throttle crispness when you’re trying to merge onto the highway or pull a grade in your Baja or Outback.

The Engineering Fix: This precision-calibrated sensor utilizes a high-grade ceramic element to detect the differential in oxygen concentration between the exhaust gas and the ambient air. By providing a clean, high-speed voltage signal to the PCM, it allows for real-time trimming of fuel injectors. The 420mm lead and correct 4-wire configuration ensure that the heater circuit reaches operating temperature rapidly, allowing your engine to exit "Open Loop" mode sooner and start saving fuel during cold starts.

Why Mechanics Choose This Kit

• Precise Fuel Trimming: Restores the factory stoichiometric 14.7:1 air-fuel ratio, essential for the high-compression D17 and the torque-heavy EJ25 platforms.
• Thermal Stability: Built with a 4-wire configuration and a robust internal heater to prevent sensor "clogging" during low-load idling or stop-and-go traffic.
• OEM-Spec Integration: Features the correct gray plug and 420mm wire length, eliminating the need for wire tucking or risky splicing that can introduce resistance and false readings.

Technical Specifications

Compatibility & OEM Reference

Fits the Following Vehicles:

• 2002-2004 Acura RSX Downstream O2 Oxygen Sensor
• 2001-2005 Honda Civic EX L4 1.7L Upstream O2 Oxygen Sensor
• 2004-2006 Subaru Baja H4 2.5L (excluding Turbo Models) Upstream O2 Oxygen Sensor
• 2003 Subaru Baja H4 2.5L Upstream O2 Oxygen Sensor
• 2003-2004 Subaru Forester H4 2.5L Upstream O2 Oxygen Sensor
• 2003-2004 Subaru Impreza H4 2.5L Upstream O2 Oxygen Sensor
• 2003-2004 Subaru Impreza Outback H4 2.5L Upstream O2 Oxygen Sensor
• 2004 Subaru Legacy H4 2.5L (excluding Turbo Models) Upstream O2 Oxygen Sensor
• 2003 Subaru Legacy H4 2.5L Upstream O2 Oxygen Sensor
• 2004 Subaru Outback H4 2.5L (excluding Turbo Models) Upstream O2 Oxygen Sensor
• 2003 Subaru Outback H4 2.5L Upstream O2 Oxygen Sensor

Interchange Part Numbers:

22641AA140, 22641AA280, 250-54011, SG1858

Package includes: 4 x Oxygen Sensor

The Performance Promise

Buy with confidence. These sensors are tested to strict quality control standards to ensure your engine maintains peak volumetric efficiency. Backed by real automotive experts and fast shipping.