I was getting codes Po401,po441,po446.[/align]I paid to the mechanic.He took out EGR valve and cleaned egr valve and its tubing with spray and then pressure wash.He put it back.After one day i did not get the codes po441 and po446 again but i got new code po401 ??Please let me know what is it.My gas cap is tight.Do i need to replace with new gas cap or should i replace the Exhaust drum on back of my Camry-2000,4cyl, 150000KM .[/align]I wanna do it myself.Please let me know the exact location of part need to be clean or replaced on front side??[/align]