my 01 Sienna last month showed engine light on, went to dealer to fix and been told code P0446 need replace by pass vacum switch valve. cost
300 and good for 3 weeks and shows light on again. from Google chat tried to tighten the gas cap and 3 days later light off but only good for 2 days; went to dealer again, this time read (P0183?) is oxygen sensor need replacedm, 400! but seems to me they just read a code and then guess/try to fix with replacing part but never show what is wrong with old part. I refused the fix this time casue I may simply pay 300 per month to lease one. never know next month which code will show up. question and help need here: is it normal that replace VSV or Oxgen sensor like routine oil change (affortable at least) ? does Toyota cover to fix emission related problem if my car failed to emission test? dose anybody ask Toyota for recall about these engine light on triggered by emission related part? is this only Toyota Sienna problem or it is generic issue.thanks