sup tech guys??

first question - is the 96-98 DX ECU same as 99-00 DX ECU? is it plug and play?

now here's the problem, we installed a o2 simulator at my friends car 2-3 months ago. everything was fine until this weekend. he was driving the car then it just starts tripping out (idling bad, ECU codes) .. he took the car home and check for the codes.

17 - ELD
20 - speed sensor
41 - o2 sensor
65 - secondary o2 sensor

a whole lot of codes... first checked the o2 sensors and the simulator. everything was in normal position except for the wiring of the primary o2 sensor. the wiring protector was melted and the wire itself was a lil open.. wire was exposed and suspected that it touched the ground and made the ECU trip out, but the o2 simulator is still in which could've made the ECU trip out more???? now he still got the codes. we reseted everything and no luck..

would it be the ECU???
thanks....