How to reset BMW computer after battery change

BMW’s have an in-board computer that controls most things. Every time you do service you need to reset it. Once you perform a battery change it is important that you update the system of the change. The main reason for this is because the computer stores electric energy which varies from the battery power.

Why you should update in-board computer of changes

When you reset the on-board computer you inform it of a new battery registration. The process is also critical for restoration of the current odometer readings. As a BMW owner you need to realize that resetting will ensure that the car’s battery registers 80% of the capacity as a reference point. When the computer is reset it also deletes some of the old battery information like voltage, temperature, charge level and current voltage.

BMW models that need computer reset

  • 7-series BMW models from the year 2002 or those having a E65/66 chassis
  • BMW 6-series from 2003 with E54/63 chassis
  • BMW X5 from 2007 with E70 chassis
  • BMW X5 from 2005 with E53 or N62 chassis
  • BMW 5 series from 2004 with E60/61 chassis
  • BMW X6 series from 2008 with E71 chassis

How to effectively reset BMW on-Board computer

  • The first thing you will need is to turn on the ignition up to the point where the lights and radio is on. This is the accessory point
  • The reset is done before starting the car
  • The next step is to press and hold the “Trip” button that is found on the instrumental panel.
  • You should press and hold until the red light comes on
  • Press the “Trip” button again and hold this time waiting for the Reset to appear
  • Press this same button again (this is the third time) and the BMW on-board computer will have reset

Most modern BMW’s come with very complicated electrical systems. Note that there is a computer program that controls the alternator and when you replace your old battery the system is supposed to know about the change. What this means is you need to inform the system even when you upgrade to a different battery type like AGM or the Absorbent Glass Mat type.

Battery reset is the process of updating the computer controlled alternator. If you do not do it you may set in motion the Diagnostic Trouble Codes (DTC) or Malfunction Indicator Lamp (MIL). Refusing to do a battery reset may cause other problems like shortening your battery life or in the worst case scenario damage entire electrical components. All these complicated systems are there to extend the lifespan of your battery and car.

A close walk into many BMW automotive stores will reveal a myriad of issues from those who fail to reset their computers after battery change. This is because the unregistered battery leads to an aggressive battery charge especially during cold weather. This further destroys the control unit.

If you are worried about the costs, it is good to know that the whole process is relatively inexpensive and not time consuming. You should be driving in no time.

How to know you have a dead car battery

Engine cranks but does not start

The first major sign that you are dealing with dead battery is when you crank up your engine and but it won’t start. It could be your starter but most of the time it is your battery. You can use jumper cables to start it but you will soon end up with the same problem. When this becomes a common issue every time you wake up in the morning for a drive then know it is time to replace your battery.

No crank, start or lights

When the car is not running, the battery powers up most of the car’s electrical components. However, when you realize that everything is dead in your car then you know your battery has issues. At times the problem can also be related to your alternator as the battery operates in conjunction with it. Note that if the car does not crank but your headlights are fine then the problem could be with your starter. You should also double check the battery terminals to ensure that they are in place before purchasing a new battery.

Intermittent starts

It is time to purchase a new battery if you notice that one day the car starts just fine then on other days you have issues starting it. You should first rule out other problems that terminals not connected well to calcification of terminals. For the latter a carbonated soda drink with a tooth brush should help you remove some of the calcification on terminals. Your battery terminals should not wiggle as you rotate them but should be firmly in place. You should also investigate any parasitic car accessory that is eating your battery power.

It could be that you went to bed with the car’s headlights on or the radios woofers are drawing too much power from the car. You will need a mechanic with a voltmeter to identify any parasitic sources draining your battery.

Cold cranking

Most batteries have on them a label with the number of amp you need to crank your engine on the first day. This what is referred to as cold cranking. You know the battery has outlived its purpose when find the car struggling to get enough power to start itself. This manifests itself when you turn on the ignition then you notice lots of weak rotations from the engine. By regular is when you experience this more than three times a week. However, you need to note that this problem can be persistent in cold weather than normal temperatures as the your gas takes time to vaporize and your oil is still very thick in such weather.


The process of resetting your car’s computer after a battery change is not costly no time consuming but it is very important if you want to avoid future problems with your alternator. Many auto shops can perform the service for you.

Jurgen Shmidt works as an automotive engineer, his duties revolve around vehicle design, development manufacture, and testing. Shmidt is also involved in marketing, sales, and the after-sale care of cars, apart from his 8 hours job, he interacts with enthusiasts who have concerns or wish to learn about the various models of the BMW luxury cars. Shmidt believes that the demand for detailed information surpasses its availability and that is why he dedicates most of his free time, researching and compiling reliable information. The information compiled on bmwexpert has been derived from hands-on experience and not some snazzy press release, thus we believe you will find answers to your troubling questions about the BMW.

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