Delphi ES20040 Oxygen Sensor - Center or Rear

Delphi ES20040 Oxygen Sensor Overview

The Delphi ES20040 is a heated oxygen sensor built for emission control service on select Ford and Mazda applications. It uses a 4-wire design, square connector, and 18 x 1.5 mm thread size to support accurate exhaust feedback in the correct vehicle position.

Backed by Delphi’s OE heritage and decades of supplier experience, this oxygen sensor brings factory-informed engineering to aftermarket replacement needs. It is listed for front, rear, and position-specific applications depending on the vehicle.

Key Features

• Heated oxygen sensor for faster operating temperature and stable signal output
• 4-wire configuration with square connector shape
• 18 x 1.5 mm thread size for direct-thread applications
• Overall length: 870.0
• Package contents include the oxygen sensor and instruction sheet
• Compatible with select Mazda Millenia, Ford Aspire, and Mazda MPV applications

Fitment Details

• Fits 1997-2000 Mazda Millenia, center, located before catalytic converter.
• Fits 1996-1997 Ford Aspire, rear.
• Fits 1991-1995 Mazda MPV, N/A.

What This Sensor Helps Address

• Check engine light caused by oxygen sensor signal faults
• Rich or lean fuel mixture concerns tied to exhaust feedback errors
• Reduced fuel economy from inaccurate air-fuel ratio correction
• Emission test failures related to sensor performance
• Slow sensor response during cold start or warm-up operation

Installation Notes

Confirm the exact sensor position for your vehicle before ordering, since this part is listed for front, rear, and position-specific use depending on application. Match the connector shape, wire count, and thread size to the original sensor, and verify the exhaust location on the application tab for Mazda Millenia, Ford Aspire, or Mazda MPV fitment.

This part cross-references DENSO Auto Parts (e.g., 234-4037, 234-4038) for the same application.

Quality Assurance

Delphi draws on 100 years of OE experience and supplier knowledge developed with top automakers, with OE heritage built into its aftermarket parts. That background supports consistent fitment and sensor design for emission control service.