Delphi ES20204 Oxygen Sensor - Rear

Rear Oxygen Sensor for Hyundai and Mitsubishi

Delphi ES20204 is a heated rear oxygen sensor built for specific Hyundai Sonata, Hyundai Elantra, Hyundai Excel, and Mitsubishi Precis applications. It uses a 4-wire design, square connector, and 18 x 1.5 mm thread size to match the listed OE-style fitment requirements.

Key Features

• Heated oxygen sensor for rear position applications
• 4-wire configuration with square connector shape
• 18 x 1.5 mm thread size for direct-thread installation
• 400.0 overall length for listed vehicle fitments
• Includes oxygen sensor and instruction sheet
• Delphi ES20204 replacement part number

Detailed Description

Delphi ES20204 is an emission control sensor for rear oxygen sensor locations on select 1993-2001 Hyundai and Mitsubishi vehicles. It is listed for rear placement on 1997-2001 Hyundai Sonata, 1996-1998 Hyundai Sonata, 1994-1995 Hyundai Elantra, 1994-1995 Hyundai Sonata, 1994 Hyundai Excel, 1994 Mitsubishi Precis, 1993 Hyundai Elantra, 1993 Hyundai Excel, and 1993 Mitsubishi Precis. Delphi draws on OE heritage and supplier experience with major automakers, and that background is reflected in the aftermarket part design.

This part cross-references DENSO Auto Parts 234-4042 for the same application.

What It Helps Address

• Rear oxygen sensor fault codes
• Incorrect exhaust oxygen readings
• Check engine light concerns related to the rear sensor circuit
• Fuel control issues caused by a worn sensor
• Emission test failures tied to sensor performance

Installation Notes and Tips

Verify the vehicle’s rear sensor location, connector style, thread size, and 400 mm overall length before installation. This Delphi ES20204 oxygen sensor is listed for rear position use only, and fitment notes vary by model year, including California emissions and date-specific applications on some vehicles. Compare the existing sensor connector and harness routing to the OE layout before replacing the part.

Quality Assurance

Delphi states that its aftermarket parts are built from OE experience and knowledge developed through long-term supply relationships with leading automakers. That OE background supports consistent fit and function for the listed Hyundai Sonata, Hyundai Elantra, Hyundai Excel, and Mitsubishi Precis applications.