Phantom Problem....engine immobilizer
 

My 04 8 has 20000 miles on it. Within the past two months my engine immobilizer will trip and shut everything down. First it started when i would come out of the grocery store or something and car wouldnt start. Key light flashing (engine immobilizer). Now it does it while im driving 65 down the interstate. It shuts everything down. Dealership ran diag., had communication errors, but couldnt find a source. Has a new ecu. No loose grounds. They were on the phone with tech support for hours trying to figure it out. anyone have any other ideas. They said it might be the fuse box is bad, but i dont want to spend $600+ because it "might" solve the problem. HELP!!!!!

I'm not very good with this, but a couple thoughts....

How many keys do you have? The keys have the chips in them. I'm not sure if it's possible if those chips malfunction, but if it does and your security no longer sees the key's chip, it could trip the EI.

If you have a second key, use it until you have the problem. If you keep both keys together, whatever damaged your first key could have damaged the second key. You can buy a new key cheap and program it (if you have two keys already) yourself in the car.

It's just a thought...I'd figure Mazda would think of this already.....but chasing ghosts isn't easy for anyone :) Good luck

Yeah, i have two keys. The first time it tripped i tried the second key. Mazda didnt seem to have a whole lot of answers. Starting to lose faith. Could be this or could be that. Starting to suck a little. Was at the dealer all day yesterday, tripped getting on the interstate this morning. It really sucks blocking traffic trying to reset your pcm. Going back to dealer on Monday.

Reset your PCM memory, warm the car up for 20 mins take it on the highway take it to redline for a few mins and make sure your plugs and everything is good. I had a problem similar to that but it happend when I came to a stop.( turbo car) i changed the plugs and coils and it never happend again.