I had an electrical problem in my 02 Civic EX... i ended up needing to replace the ECU (got one from a junk yard... from another 02 EX)... I had to have it re-flashed at the dealership to work with my security codes. Now my check engine light is on and it's reporting an O2 sensor failure... i have replaced the O2 sensor and cleared the code, but it came back on and is reporting the same code again. I checks the wires running from the O2 sensor to the ECU and it there is no signal... do you think it might be the ECU itself, or maybe just the software flash wasn't correct (e.g. for a non-vTec motor or LX or DX model)