Denso 234-5003 Air / Fuel Ratio Sensor - Upstream

Denso OE Style Air/Fuel Ratio Sensor

Denso 234-5003 is an OE Style heated air/fuel ratio sensor built for specific-fit replacement on select Subaru and Cadillac applications. It is engineered to match factory-style fitment and signal requirements for accurate air/fuel monitoring in the exhaust stream.

For drivers searching for a direct replacement air fuel ratio sensor for 2000-2002 Subaru Forester, Impreza, Legacy, or Outback upstream locations, this Denso sensor is built to install with the correct connector and harness layout. It also fits 2004-2005 Cadillac XLR upstream with OE-style application notes.

Key Features

• Part number: 234-5003
• OE Style replacement from Denso
• Heated sensor design
• Specific fit for confirmed vehicle applications
• 5-wire configuration with male connector
• Wiring harness length: 20.28
• Thread diameter: 0.711
• Built and tested to OE-level standards for fit and function

Product Details

Denso 234-5003 is an emission control sensor designed to monitor the air/fuel ratio and support engine management on compatible vehicles. The OE Style line focuses on exact replacement dimensions and first-time fit, which helps reduce installation issues on applications such as 2000-2002 Subaru Forester upstream and 2004-2005 Cadillac XLR upstream. This part number 234-5003 is also a direct search match for buyers comparing Denso 234-5003 against other OE-style replacement sensors.

This part cross-references Bosch 15493 and NTK 24320 for the same application.

What It Helps Address

• Check engine light related to air/fuel sensor performance
• Rough idle caused by incorrect mixture feedback
• Poor fuel control from a failing upstream sensor
• Delayed or inaccurate oxygen sensor-style signal response
• Emissions test failures tied to sensor faults

Installation Notes and Tips

• Confirm the vehicle is listed in the fitment data before ordering.
• Use the upstream position only where specified.
• Match the connector style and 5-wire layout to the original sensor.
• Inspect the harness routing and thread engagement before final tightening.
• Clear diagnostic trouble codes after installation and verify live data response.

Quality Assurance

Denso manufactures and tests this OE Style sensor to strict original-equipment standards. The design emphasis is on precise replacement dimensions and correct fit for the listed Subaru and Cadillac applications, including 2000-2002 Subaru Forester, Impreza, Legacy, and Outback, plus 2004-2005 Cadillac XLR.