Delphi ES20125 Oxygen Sensor

Delphi ES20125 Oxygen Sensor for BMW

The Delphi ES20125 is a heated oxygen sensor built for select BMW applications that require a front-position sensor with a 1520 mm overall length. It uses a 4-wire design, a round connector shape, and an 18 x 1.5 mm thread size for OE-style replacement fitment.

Backed by Delphi’s OE heritage and more than 100 years of supplier experience with major automakers, this oxygen sensor is engineered with production-level knowledge carried into the aftermarket. It is a direct-fit option for BMW 535i, M5, 735i, 735iL, 635CSi, and 535is applications listed below.

Key Features

• Heated oxygen sensor for front-position applications
• 4-wire configuration for signal and heater circuit operation
• Round connector shape for OE-style connection
• 18 x 1.5 mm thread size
• 1520 mm overall length
• Package includes oxygen sensor and instruction sheet
• Delphi ES20125 part number for easy identification

Detailed Description

The Delphi ES20125 oxygen sensor is designed for BMW exhaust systems that call for a heated front sensor with the specified connector, thread, and lead length. It supports accurate exhaust feedback to the engine management system, helping maintain proper air-fuel control and emissions monitoring. This part cross-references Bosch 13052 for the same application.

Compatible With 1988-1993 BMW 535i, front; 1991-1993 BMW M5, front; 1988-1992 BMW 735i, front; 1988-1992 BMW 735iL, front; 1988-1989 BMW 635CSi, front; and 1988 BMW 535is, front. The Delphi ES20125 is a practical OE-style replacement for these BMW models when the original sensor matches the listed dimensions and connector style.

Common Issues This Sensor May Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel mixture readings
• Reduced fuel control from a slow or aging sensor
• Emissions test failure caused by faulty exhaust feedback
• Driveability concerns tied to inaccurate sensor output

Installation Notes and Tips

Verify the vehicle’s sensor location, connector shape, thread size, and lead length before installation. This front oxygen sensor is specified with a 1520 mm overall length, so matching the original routing and reach is important on BMW 535i, M5, and other listed applications. Inspect the exhaust bung threads and connector condition before installation to help ensure a proper fit.

Quality Assurance

Delphi builds aftermarket parts using OE experience gained from supplying major automakers, and that heritage is reflected in the ES20125 oxygen sensor design. The part number ES20125 helps confirm the correct replacement for the listed BMW applications.