Delphi ES20123 Oxygen Sensor - Center, Rear or Rear Left

Delphi ES20123 Oxygen Sensor Overview

Delphi ES20123 is a heated oxygen sensor built for emission control service on select Mazda applications. It uses a 4-wire design, a square connector, and an 18 x 1.5 mm thread size for direct replacement in the specified center, rear, and rear left positions.

Backed by Delphi’s OE heritage and decades of supplier experience with major automakers, this oxygen sensor reflects the engineering knowledge used in original equipment development. It is a practical choice for Mazda 6, Protege, Protege5, and MPV service where accurate exhaust feedback is required.

Key Features

• Heated oxygen sensor for emission control service
• 4-wire configuration
• Square connector shape
• 18 x 1.5 mm thread size
• Overall length: 660.0
• Includes oxygen sensor and instruction sheet
• Positions: center, rear, rear left, depending on vehicle application

Detailed Description

The Delphi ES20123 oxygen sensor is engineered for select Mazda exhaust systems that require a heated sensor in the center, rear, or rear left location. It is listed for 2005-2008 Mazda 6 with California Emission System, 1999-2003 Mazda Protege rear, 2002-2003 Mazda Protege5 rear, and 2000-2001 Mazda MPV rear left with California Emission System. This part number, ES20123, is a direct-fit service option for those confirmed applications.

This part cross-references Bosch 13688 and DENSO Auto Parts 234-4752 for the same application.

What It Helps Address

• Fault codes related to oxygen sensor performance
• Incorrect exhaust oxygen readings
• Rough idle or drivability issues tied to sensor feedback
• Failed emissions inspection caused by a worn sensor
• Reduced fuel control accuracy from aging exhaust sensors

Installation Notes and Tips

• Verify the exact position on your vehicle before ordering; this part is listed for center, rear, and rear left locations.
• Confirm thread size and connector shape match the original sensor before installation.
• Inspect the exhaust bung and wiring routing for damage, corrosion, or heat exposure before replacing the sensor.
• Use the vehicle application details to confirm fitment for Mazda 6, Mazda Protege, Mazda Protege5, or Mazda MPV.

Quality Assurance

Delphi draws on 100 years of OE experience and supplier knowledge developed with leading automakers, and that OE heritage is built into its aftermarket parts. The ES20123 is produced to support the fitment and service expectations of the listed Mazda applications.