So i purchased a car with a p28 ecu and i also got the stock one from the guy, so i switched out the ecu to stock p2t or something, and check engine came on. So what do I have to do to make it go away. He told me that when he put in the p28 ecu it came on and his friend hooked it to the computer to get rid of it. So does the car think it is a obd1 now or something i just replaced o2 sensors, i really need to pass smog, the p28 will pass smog now i think but im not sure because it has a chip that probably throws more fuel into the motor and changes the redline to like 9000, I'm running rich. So what should I do any help, or expediences.