Computer need to be reset?

Tiny
ANONYMOUS
  • MEMBER
  • 2006 MERCEDES BENZ E350
  • 70,000 MILES
After changing battery does computer need to be reset if so how
Thursday, January 10th, 2013 AT 4:20 AM

2 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,742 POSTS
You did that by disconnecting the battery. The various computers lose their memory. What needs to be "reset" is the "look-up tables" the Engine Computer uses to determine how much fuel to command for any combination of operating conditions. It will start out with factory-programmed values, then begin to modify and adjust those numbers while you drive. Most of the time you won't even know that is taking place.

Most battery installers avoid the need for computers to relearn operating characteristics by using a "memory saver" device. Typically they use a nine volt transistor battery and plug into the cigarette lighter. You have to be careful with those to not open a door, turn on the under-hood light, or turn on the ignition switch. That tiny battery is too small to run lights and the fuel pump and will in effect be shorted out. I connect a small battery charger to avoid having to reset clocks and radios for customers, but that has its own precautions and dangers.
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Friday, January 11th, 2013 AT 9:57 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,895 POSTS
You will need to keep it running by holding your foot on the throttle until the idle relearns itself. This works for most car sometimes when you connect the battery you will get a voltage spike in which case the computer will need to be re-initiated.

Please let us know what happens.

Cheers, Ken
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Tuesday, February 20th, 2018 AT 3:46 PM

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