My g35 03 130k has failed the smog test. The code is p0057. I replaced both downstream with NTK. I also checked all wiring and fuses and they are fine. I was forced to go to 4 mechanic shops including the stealership. One mechanic told me i might need new catalyc converters but her is not sure it will fix the problem. The other said to contact the stealeship. The stealership said its an electrical problem and i might need a new ECM. Anyone has a similar problem? Ive spent too much trying to fix it and would like advice before i purchase and install an ECM.