I have a 05 G6 and we had torrential rain the other night. Went to use my car yesterday and noticed the engine light, traction control light, service engine soon lights were all on and reduce engine power was on the display. I also notice A LOT of water on the floor of back passenger side. I let it sit all day yesterday...had more rain last night and this morning and took it to my mechanic to look at it tomorrow. All of the lights but the engine light were off but the back passenger side floor was STILL full of water! Is this all from water damage and if not, what else could it be? Is this something that is going to cost me an arm and leg? Ive read a lot about leaking sunroof drains (I have a sunroof) but find it hard to believe the lights and reduce engine power display is all because of that. Any help would be great. Thanks.