I am 19, live with my dad and have a 2004 RX-8 in good condition. I left for North Dakota in august and lived there a month for work. During that time my dad washed and waxed it for me, using a different key to start it than my usual key. I come home, try to start it, and the immobilizer light is flashing (it hasn't been driven for a week of two since being washed). It wants to start, the engine gets going and everything, but the immobilizer is stopping it. Could this be because a different key was used or is it indicative of an underlying problem?

 

look for recalls, i remember seeing others on the forum with immobilizer issues. You can also follow the key programming procedure in the owners manual.