Round 20 Pin Port to 16 Pin OBD2 Adapter Cable for BMW

Connect modern OBD2 scanners to your classic BMW's 20-pin diagnostic port—enabling full diagnostics on E30, E36, E34, E39, Z3, and X5 models built before the industry-standard 16-pin OBD2 port became mandatory.

The Essential Tool for Diagnosing Classic BMWs

If you own a 1986-2001 BMW—E30 3 Series, E36 M3, E34 5 Series, E39 M5, Z3 roadster, or early X5—you've discovered that modern OBD2 scan tools won't plug directly into your car. BMW used a proprietary round 20-pin diagnostic connector on these models, years before the automotive industry standardized on the 16-pin OBD2 port in 2001. This left owners of these legendary BMWs unable to use affordable modern scanners for basic diagnostics like reading fault codes, clearing check engine lights, resetting service indicators, or monitoring engine parameters. Professional BMW-specific diagnostic equipment costs thousands of dollars, putting proper diagnostics out of reach for most enthusiast owners.

This adapter cable solves that problem by converting your BMW's 20-pin round diagnostic port to the standard 16-pin OBD2 connector. Simply plug the 20-pin end into your BMW's diagnostic port (typically located in the engine bay near the strut towers or firewall), connect your OBD2 scanner to the 16-pin end, and you're ready to diagnose. The adapter enables full communication with your BMW's engine control unit, ABS system, airbag module, and other onboard computers—allowing you to read and clear fault codes, perform service resets, and access live data. Research shows owners successfully use this adapter with affordable Bluetooth OBD2 scanners, dedicated BMW diagnostic software like INPA, and universal code readers. One E39 528i owner confirmed the adapter works perfectly for resetting oil service intervals and clearing airbag codes, while a Z3 owner used it to connect laptop-based INPA software for advanced diagnostics.

Key Features

• 20-Pin to 16-Pin Conversion: Connects modern OBD2 scanners to BMW's proprietary round 20-pin diagnostic port
• Plug-and-Play Design: No modifications required—simply connect the adapter and your scanner is ready to communicate
• Full Diagnostic Access: Enables reading and clearing fault codes, service resets, live data monitoring, and more
• Durable Construction: Quality terminals and ABS plastic housing ensure reliable connection and long-term durability
• Essential for Classic BMWs: The only way to use affordable modern diagnostic tools on pre-2001 BMW models

Fitment (BMW Models with 20-Pin Round Diagnostic Port)

3 Series:

• E30: 1986-1991 (318i, 318is, 325i, 325is, 325ix, M3)
• E36: 1991-1999 (318i, 318is, 318ti, 320i, 323i, 323is, 325i, 325is, 328i, 328is, M3)

5 Series:

• E28: 1982-1988 (524td, 528e, 533i, 535i, 535is, M5)
• E34: 1989-1996 (525i, 530i, 535i, 540i, M5)
• E39: 1996-2001 (525i, 528i, 530i, 540i, M5)

6 Series:

• E24: 1976-1989 (630CSi, 633CSi, 635CSi, M6)

7 Series:

• E23: 1977-1986 (733i, 735i, L7)
• E32: 1987-1994 (730i, 735i, 735iL, 740i, 740iL, 750i, 750iL)
• E38: 1995-2001 (740i, 740iL, 750i, 750iL)

8 Series:

• E31: 1990-1999 (840Ci, 850Ci, 850CSi)

Z Series & X Series:

• Z3: 1997-2001 (all models including M Roadster and M Coupe)
• X5 (E53): 1999-2001

Note: This adapter is for BMW models with the round 20-pin diagnostic connector. Verify your vehicle has this port before ordering (typically located in engine bay). Not compatible with newer BMWs that already have standard 16-pin OBD2 ports.

What You Can Do:

• Read and clear engine fault codes (check engine light)
• Access ABS, airbag, and other system codes
• Reset service indicators (oil change, inspection reminders)
• Monitor live engine data (RPM, coolant temp, fuel trim, etc.)
• Use with Bluetooth OBD2 adapters and smartphone apps
• Run BMW-specific software like INPA, DIS, or NCS Expert

Package Includes: 1x BMW 20-pin to 16-pin OBD2 adapter cable (approximately 28c