An '04. Just picked it up from a friend last week. Was in the driveway with the doors open (interior lights on) radio playing while I learned how to reprogram it to my tastes. After about 20-30 min, I see a "Low Battery" message on the dash info screen. Hmmm. I started the car and continued programming. Next morning, by coincidence, I get a Check Engine light. Hmmm. I'm figuring it was related to some weird behavior due to the battery, which was the original from '04 I think, so 11 years later, I'm not surprised! I brought it to my friend at the auto parts store and he puts his elec. system analyzer on the battery, while still hooked up. It's reading 0 CCA, yet still starts the car. So we disconnect it from the car, and then get 270 cca, but he can't continue the test deeper to check the alternator because the scanner is saying "interference", which in his experience, means something is still on or draining with the car off and all doors closed. We also tried the scan from up front on the aux (for jump starting) terms too and still got the "interference" message but strangely, an increase in CCA to 400, still kinda weak but better. We put the new battery in anyway and got the same results. 0 CCA in the back, and the "interference" message, so we still don't know the health of the alternator. BUT, any ideas on what would cause the interference or what would be a drain with the car off? Bear in mind, it never died or needed to be jumped while my buddy owned it, nor for the 5 days I've owned it. Starts a few turns into the cycle, no problem. Thanks!