All ecus are locked from the manufacture. Every car every ecu. It's been reverse engineered that's all.
Ecuflash, Cobb & EcuTek knows how to get in it etc.
When EcuTek programs the ecu security is changed so the tune and ecuteks custom ecu logic isn't taken out via Ecuflash.
Cobb does the same thing on 04+ cars, the big difference is the customer owns a hand held and can remove it anytime he wants. EcuTek doesn't have a handheld, just a flash cable that can be purchased by the customer...no one ever buys them. So when they want to switch or remove they need to find a Ecutek dealer.
02-03 ecus are the same, no one has ever been able to explain what's different about them.
But like I said before, if you have a car and need Ecutek taken off let me know and I'll help you out the best I can.