Delphi ES10221 Oxygen Sensor

Delphi ES10221 Oxygen Sensor Overview

The Delphi ES10221 is a non-heated upstream oxygen sensor built for emission control applications that require accurate exhaust feedback. It reflects Delphi’s OE heritage and decades of supplier experience, bringing factory-informed engineering to the aftermarket.

Compatible with select Ford Festiva, Mazda B2600, Mazda RX-7, and Mazda 626 applications with a 400 mm overall length, this oxygen sensor is a direct-fit option for vehicles that use the specified thread, connector, and wire configuration.

Key Features

• Non-heated oxygen sensor for upstream placement
• Square connector shape for application-specific fitment
• 18 x 1.5 mm thread size
• 400.0 mm overall length
• 1-wire design
• Package contents include the oxygen sensor and instruction sheet
• Delphi ES10221 part number for easy identification

Detailed Description

The Delphi ES10221 oxygen sensor is engineered for emission control systems that rely on upstream exhaust monitoring. Its non-heated design, single-wire construction, and square connector support the original equipment-style configuration used on select older Ford and Mazda applications. This part number is commonly searched for as Delphi ES10221 oxygen sensor, upstream oxygen sensor, and 400 mm oxygen sensor replacement for Ford Festiva and Mazda models.

This part cross-references Bosch 12054 and DENSO Auto Parts 234-1019 for the same application. It also aligns with select interchange references including 138-143 and 0258002054.

What It Helps Address

• Check engine light concerns related to oxygen sensor signal faults
• Incorrect exhaust oxygen readings affecting fuel control
• Rough idle or drivability issues tied to sensor degradation
• Failed emissions testing caused by a worn upstream sensor
• Restoration needs on older Ford and Mazda emission systems

Installation Notes and Tips

Verify the vehicle uses an upstream, non-heated sensor with a square connector and 18 x 1.5 mm thread before installation. Confirm the 400 mm overall length matches the original routing and connector reach on the application. Fits 1988-1989 Ford Festiva, N/A; Fits 1988 Mazda B2600, N/A; Fits 1985-1988 Mazda RX-7, N/A; Fits 1985 Mazda 626, N/A.

Quality Assurance

Delphi builds aftermarket parts using OE experience and supplier knowledge developed through work with major automakers. The ES10221 is backed by that OE-focused engineering approach for emission control service.