Uprev is the issue but its completly random some of the time when you flash an ecu with their software it will set one of the u codes for "insert module here" to ecu can failure. I have seen u1024 u1023 and others sometimes multiples. Some times a different map fixes it sometimes using an older or newer revision of your rom fixes it and sometimes you have to get one of the expensive boxes replaced. All I know is it only happens to reflashed ecu's specifically with uprev.