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BMW Diagnostic Port – "D" Vs. Round Vs. DLC Vs. OBD-II

November 3, 2010

This answer is applicable for many BMWs in addition to the one listed below.

Q
Could you advise if my 1989 325ic is equipped with a OBD11 diagnostic port, and if so, where it is located.

A
Your 89 model BMW does not have an OBD-II diagnostic port, or OBD-II engine management.

The first year for OBD-II compliance is 1996.  All vehicles sold in the US, from 1996-on must comply with the mandated On Board Diagnostics – Version II (OBD-II).  These models will have the rectangular OBD-II port located in the passenger compartment, on the driver’s side.  Common locations (for BMWs and MINIs) are in the center console, in the under-dash trim panel or in the side kick-panel (forward of the door).

BMW models prior to the OBD-II mandate have BMW specific on board diagnostics and the Data Link Connector port (DLC) is located under the hood.  Early models (through 87/88) have a smaller “D” shaped port that is typically mounted at the front area of the engine.  Later models (87/88-on) use the Motronic 1.1 engine management and have larger round DLC ports.  These may be mounted to the engine or off the engine on the left or right inner fender.

Your 89 325ic has the round DLC port and it is located at the front of the engine, just behind the thermostat housing, in front of the intake manifold.

We are currently building a library of underhood item location videos for the various BMW and MINI chassis.  Search our blog for “underhood video” to see what we currently have available.

Example of DLC port location on 5-series 91-96, 6-cylinder:

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