As we know all cars included BMW’s diagnostic OBD codes can be accessed through the car’s data link connection (DLC). For 5 series BMW’s manufactured in 2009, this outlet is under the steering wheel and to the far left. You will have to remove a cover to get to it. You can retrieve the BMW 525’s diagnostic codes with an OBD-ii scanner. This will tell you why your check engine light has activated on your instrument panel.
You’ll Need OBD 2 code scanner for this job.
Uncover the data link connection and connect your OBD-ii scanner to it.
Use your BMW’s ignition key to start the electrical system, but do not crank the engine.
Enable the scanner. How to do this relies on the scanner that your are using. Some power themselves on automatically when data streams in from the BMW’s diagnostic system and some require the user to manually power the scanner on if you do not have this feature, but always look up your manual ahead of time.
Watch the scanner’s read-out screen. As soon as the BMW’s computer link to the OBD scanner, all current diagnostic trouble codes will display on the read-out screen.
Consult the reported codes in your scanner’s manual. It will include generic codes common to all cars. Some scanner’s manuals will include supplemental diagnostic codes too. BMW created these codes and they may not be in your 525’s owner manual, but they can be easily looked for in some of the non-BMW affiliated websites that list all OBD-ii codes.
Read the code description very carefully. If it sounds like something very difficult to you, you may not want to attempt the fix yourself. However, once you drive the 525 to a BMW approved and professional mechanic, you can explain what the problem is and save yourself from being charged a diagnostic code fee.