Delphi ES20421 Oxygen Sensor - Rear
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Delphi

Delphi ES20421 Oxygen Sensor - Rear

Brand Delphi ES20421
Position Rear
Connector Shape Flat
Overall Length 765.0
Package Contents Oxygen Sensor, Instruction Sheet
Position(s) Rear, Rear Left. For the position specific to your vehicle, refer to the Application tab.
Sensor Type Heated
Thread Size 18 x 1.5 mm
Wire Quantity 4
Fits BMW · 82 vehicles

Heated sensor. Delivers faster operation for responsive emissions monitoring.

Flat connector. Simplifies installation with a straightforward electrical connection.

OE heritage. Built with 100 years of OE experience and supplier knowledge.

Cross-references DENSO Auto Parts 234-4479, Remy 16162 and 11 78 7 589 475 for the same application. See all 6.

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Delphi ES20421 Rear Oxygen Sensor

The Delphi ES20421 is a heated oxygen sensor built for rear exhaust monitoring on select BMW applications. It combines OE-based engineering with a 4-wire design, flat connector shape, and 18 x 1.5 mm thread size for direct-fit replacement needs on covered vehicles.

Key Features

  • Heated oxygen sensor for rear exhaust position monitoring
  • 4-wire configuration with flat connector shape
  • 18 x 1.5 mm thread size
  • Overall length: 765.0
  • Package contents: oxygen sensor and instruction sheet
  • OE heritage backed by Delphiโ€™s long history supplying automakers

Product Details

Delphi ES20421 is engineered for rear sensor applications where accurate exhaust feedback is needed to support emissions system operation. Delphi draws on OE experience and supplier knowledge developed over decades, and that background is reflected in the sensor design and application coverage. This part cross-references DENSO Auto Parts 234-4479 for the same application. It is a direct replacement option for BMW 640i, BMW X3, BMW 535i, BMW X5, and other listed rear-position applications, including select rear left use where specified by vehicle application data.

What It Helps Address

  • Check engine light related to rear oxygen sensor performance
  • Fault codes tied to slow sensor response or heater circuit issues
  • Incorrect exhaust feedback affecting emissions monitoring
  • Rear sensor replacement on high-mileage BMW vehicles
  • Restoring proper signal input to the engine management system

Installation Notes

  • Verify the exact rear position for your vehicle before ordering.
  • Confirm connector shape, wire count, and thread size match the original sensor.
  • Some listed BMW applications note harness length differences or date-specific coverage.
  • Use the application tab to confirm fitment for your year, model, and position.

Quality Assurance

Delphi builds this oxygen sensor using OE-focused engineering and manufacturing knowledge developed through years of supplying major automakers. The ES20421 is intended for covered BMW rear sensor applications and is supported by the included instruction sheet.

Related reading

This part fits 82 vehicles
Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.
YearMakeModelSubmodelPositionNotes
2017BMW640i—Rear—
2017BMW640i Gran Coupe—Rear—
2017BMW640i xDrive—Rear—
2017BMW640i xDrive Gran Coupe—Rear—
2017BMWX3—Rear—
2016BMW335i GT xDrive—Rear—
2016BMW535i—Rear—
2016BMW535i xDrive—Rear—
2016BMW640i—Rear—
2016BMW640i Gran Coupe—Rear—
2016BMW640i xDrive—Rear—
2016BMW640i xDrive Gran Coupe—Rear—
2016BMWX3—Rear—
2016BMWX4xDrive35iRear—
2015BMW335i GT xDrive—Rear—
2015BMW535i—Rear—
2015BMW535i xDrive—Rear—
2015BMW640i—Rear—
2015BMW640i Gran Coupe—Rear—
2015BMW640i xDrive—Rear—
2015BMW640i xDrive Gran Coupe—Rear—
2015BMW740i—RearHarness Length 690mm
2015BMW740Li—RearHarness Length 690mm
2015BMW740Li xDrive—Rear—
2015BMWActiveHybrid 7—Rear—
2015BMWX3—Rear—
2015BMWX4—Rear—
2014BMW335i GT xDrive—Rear—
2014BMW535i—Rear—
2014BMW535i GT—RearTo 08/2013
2014BMW535i GT xDrive—RearTo 08/2013
2014BMW535i xDrive—Rear—
2014BMW640i—Rear—
2014BMW640i Gran Coupe—Rear—
2014BMW640i xDrive—Rear—
2014BMW640i xDrive Gran Coupe—Rear—
2014BMW740i—RearHarness Length 690mm
2014BMW740Li—RearHarness Length 690mm
2014BMW740Li xDrive—Rear—
2014BMWActiveHybrid 5—Rear—
2014BMWActiveHybrid 7—Rear—
2014BMWX3—Rear—
2014BMWX6—Rear—
2013BMW135i—Rear—
2013BMW335i—Rear—
2013BMW535i—Rear—
2013BMW535i GT—Rear—
2013BMW535i GT xDrive—Rear—
2013BMW535i xDrive—Rear—
2013BMW640i—Rear—
2013BMW640i Gran Coupe—Rear—
2013BMW740i—RearHarness Length 690mm
2013BMW740Li—RearHarness Length 690mm
2013BMW740Li xDrive—Rear—
2013BMWActiveHybrid 3—Rear—
2013BMWActiveHybrid 5—Rear—
2013BMWActiveHybrid 7—Rear—
2013BMWX3—Rear—
2013BMWX5—Rear—
2013BMWX6—Rear—
2012BMW135i—Rear—
2012BMW335i—Rear—
2012BMW535i—Rear—
2012BMW535i GT—Rear—
2012BMW535i GT xDrive—Rear—
2012BMW535i xDrive—Rear—
2012BMW640i—Rear—
2012BMWActiveHybrid 5—Rear—
2012BMWX3—Rear—
2012BMWX5—Rear—
2012BMWX6—Rear—
2011BMW135i—Rear—
2011BMW335i—Rear—
2011BMW528i—Rear30in Length
2011BMW535i—Rear—
2011BMW535i GT—Rear—
2011BMW535i GT xDrive—Rear—
2011BMW535i xDrive—Rear—
2011BMWX3—Rear—
2011BMWX5—Rear—
2011BMWX6—Rear—
2010BMW535i GT—Rear—
Directly replaces or cross-references 6 part numbers
Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.
DENSO Auto Parts — 234-4479Remy — 1616211 78 7 589 47511 78 7 603 0222573025740