my pug sounds like a jumbo jet

can anyone help me i've got a pug 106 x reg last week engine mnagement light came on got it tested and new lamba sensor was fitted all was great for about a week and now my car sounds like a jumbo jet when driving over 1500rpms no warning lights are on and car starts 1st time don't know if any relevance but both faults occured after heavy rain . was wondering if it could be the new sensor would appreciate any ideas cheers