Hi Rich-

First, it gets a little complicated on BMW's as there are multiple system. The core engine codes are compliant with the OBDII standard and can be read by lots of code readers. However, BMW's also have their own proprietary system on top of that (using the same connector port, but providing more data in a non-standard format). In particular, things like airbag sensors or individual wheel speed sensors are a good example. Finally, there are certain things you can reset through this interface - often referred to as "adaptations". On newer BMW's (but not E53 I believe) this includes reseting the way the computer charges the battery when you change the battery and reset parameters for the transmission if you change the fluid, etc.

There are two components - you will need some sort of cable to attach a laptop to the port on your BMW (or a bluetooth wireless interface, or a dedicated scanner with its own cable) and then software for a laptop or the dedicated device with its own software to actually communicate with the car.

I would break the search for code readers down into perhaps three levels.

1) The cheapest/simplest ones read only generic OBDII codes and are of limited use on a BMW, but may report and be able to clear codes for basic engine problems. There are some bluetooth enable versions that can interface with an Android phone if you happen to have one (no reasonable choices for Apple iOS that I know). Starting around $20. These are not able to clear all codes and can not reset adaptations.

The middle level are some proprietary software packages that run on a laptop (I use AutoEnginuity). Snap-On sells one too that is typically pricey. At this level, the software should be able to read all the various systems and clear codes within those systems and reset adaptations. $300 and up.

The highest level is the least expensive, but requires finding an eBay copy of the official BMW software package (INPA, etc) and installing that on a laptop - most people dedicate a laptop to this for security and stability reasons - this provides the greatest access and detail, and doesn't even cost that much, but does require a HIGH level of comfort with Windows PC's and programming. $50 on eBay.

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David.X5
2001 X5 4.4i Sport
SOLD! at 160k miles