Jon996

SORRY if this is repeat, but I spent a lot of time paging thru battery threads tonight, and did not see anything.

Is there any (SAFE) way to preserve the codes (ECU, radio, etc) which changing batteries? Would the battery maintainer that works thru the lighter keep the codes in order?

wross996tt

What codes do you need? You have an '03 so the DME saves the radio code. There is no ECU code to save so to speak. You may reset the ECU, but it will quickly learn your driving style again...

chsu74

What if the question pertains to '99 - '01 cars? I was thinking the same thing myself recently.

Excellence had an excellent article recently on how to tell if your alternator and battery is healthy using the volt meter. I remember as far as the volt meter should go up to 14 volts after start up showing the alternator is healthy.

There is also another section on turning on the lights without starting the car and seeing how far the voltage goes down and what deems it a battery in weak or healthy condition.

Jon996

Thanks--I did not know this! Sounds like no problem then!

gota911

When I recently replaced the battery in my '04, everyting worked immediately except for the radio stations I had previously programmed to the buttons.

However, give the radio some time, 5 minutes or so, to reload stations you have previously stored in the system. I began immediately to reset the stations and by the time I was finished with the 4th button, I noticed that buttons 5 - 8 were back to the original programming.

wross996tt

The only thing you lose (as far as I can tell) is any changes you have made to the instrument panel display...like temp, boost, etc...

pat056

+1. That's all I lost when I disconnected the battery...the water temp. code which you guys quickly helped me reset.

Irksome

You also lose the engine monitors needed to pass a smog check (in CA). If your battery dies or is disconnected, you need to drive the car until it is damned well good and ready to let you pass smog. No one seems to be able to determine exactly how much driving of what kind is needed, either.

JonesnSince78

Click on pic for link...

chsu74

Awesome!! Thanks for the link.

wrljet

That 9V battery clip won't work if the dome lights or trunk lights are on.
Battery won't have enough umph to supply the required current.

chsu74

how do you change the battery without the trunk open? do you pull the trunk light bulb?

MikeZ

I would guess that the plug in (cigar liter) battery maintainer would also work. Am I correct?

wross996tt

I believe so...just make sure the connection is not interrupted (Porsche cigar lighters are wider and shorter than standard).