How to reset BMW computer?
Robert King 
A computerized engine-management system manages the fuel/air mix and timing to optimize performance. It uses input from many sensors to measure, for example, air temperature, throttle position, crankshaft speed (and by extension load), coolant temperature, knock sensor input (possible impending detonation), etc., and adjusts ignition timing accordingly. A mechanic can usually diagnose problems by observing symptoms such as rough idle or stalling after the car is warmed up. Newer cars have self-diagnostic capabilities that can be viewed without a scan tool; these systems provide error codes via the “M” display on newer BMWs, which will likely require a trip to the dealership if it sounds like your has an issue.
Although resetting the computer may seem like a daunting task, it is a relatively easy process that can be completed in just a few minutes.
To reset the computer on a BMW, you will need to locate the hidden diagnostic port. This is usually located near the steering column, below the dashboard on the driver’s side. Once you have found the diagnostic port, insert the metal end of the reset tool into the hole and hold it there while you turn on the ignition. You should hear a “click” when it’s in place. Then, turn off the ignition and remove the tool. That’s all there is to it!
If your BMW doesn’t have an electronic key (i.e., keyless start), then you will need to use the key to turn on the ignition and then press and hold the trip reset button while you turn off the ignition. The trip reset button is usually located near the steering column, below the dashboard on the driver’s side.
It’s a good idea to reset your BMW’s computer every time you have it serviced at a dealership. This will ensure that any changes that are made during the service are properly accounted for by the computer. It’s also a good idea to reset the computer if you’re experiencing any performance problems with your car. By following these simple instructions, you can quickly and easily reset your BMW’s computer without having to take it to a mechanic.
