My dad was having problems with the alarm on his 99 sedan, but we didn't know the reason. The dealership said it might be because the battery was drained but we weren't having any other battery problems. But when I was installing my cd changer into his car, we left the doors open for 15 minutes or so and the battery died. We jumped it and got it working again (fortunately it didn't need a jump every time after that). But the next day he was driving it and the check engine light came on. We didn't know what caused it so we looked in the manual and it said something to do with emmissions or something like that. There's a completely different light for the battery/charging system so we didn't think it was for the battery, but thought we might've screwed up some of the wires in the car when taking apart the dash and console. Well he got the battery checked out and replaced today and the check engine light went out, so apparently it was caused by the low battery. Anyone else have this problem or seen this before? I thought it was wierd to have the battery cause the check engine light to come on rather than the battery light.