Old post! I can tell you that a bad sensor isn't the solution, I actually had to drive my car with a varified bad sensor and the car started and ran fine for a week. I did this when I was swapping my header with the greddy, my stock 02 sensor wouldn't come off the stock downpipe, so I went ahead and unplugged it from the engine, installed my greddy header and popped in the bad 02 sensor. I was later able to take my good sensor off my stock down pipe and install it to the greddy pipe.