Civic Coupe VTI 1999.

If car has been remapped, will disconnecting battery for a long time cause any remaps to be reset?


No, it shouldn't. During a remap, there are tables which the ECU reads to know what/when/how fueling and other events should occur. This is in non-volatile memory. There are other parts of the ECU which will be wiped out, such as error codes and the fine adjustments the vehicle does to itself to get the tune "just right", which is in volatile memory.

  • That's all correct, but I have had an ECU totally erase its EEPROM on me on one occasion while swapping the battery (2010 Chevy Impala). No sparks or mixed up wires. – EᑎOT Oct 2 '20 at 20:50
  • @Enot - While I can only assume what you are saying is correct, I'd bet there was some contributing factor which caused your ECU to take a dump. It doesn't happen like that very often and it's definitely not the norm, nor how it was designed to work. Every battery swap would cause a need for a remap. Sounds like your car really took a dump on you! :o( – Pᴀᴜʟsᴛᴇʀ2 Oct 3 '20 at 0:43
  • @Paulster2, yeah, Chevys tend to do that, don't they. :) Actually, I believe that in the manual for that car it says to maintain 12V to the car terminals while replacing the battery. – EᑎOT Oct 3 '20 at 22:46
  • @Enot - That's usually so you don't lose the presets on your radio. – Pᴀᴜʟsᴛᴇʀ2 Oct 3 '20 at 22:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.