I have a 2004 Mazda6 3.0L. So my ECU needs to be replaced, the car doesn't start in cold weather unless I warm up the ECU by hand (heat gun or hot towel, at which point is starts up fine), thanks to mazda6club I tracked down the solution. I've seen posts that intsalling another used ECU simply requires a dealer reflash and key programming.

My local dealership (Bakersfield, CA) is telling me it is impossible, that they can only program the "immobilizer" but not totally reflash the ECU, and the particular issue this guy makes is that the "federal" (non-CA emissions) software may not be compatible with my CA vehicle and that they cannot flash my used ECU to identicle specs as the one in my car. I'm thinking that this is BS, since I'm sure flashing a ECU must be similar as flashing most other electronic gadgets, i.e. replacing the data on some ROM chip. Two other dealerships that I've called, which unfortunately are at least an hour away, have said they can do what I'm asking and have made no mention of not being able to do it. The Long Beach dealership tech says all they need to do is get the Asbilt (sp ?) data directly from Mazda and flash the vehicle.

Is the Bakersfield service guy yanking my chain? he quoted me about $1100 for install of a new ECU.