Learned a $20 Bluetooth OBD2 scanner tells you more than a $200 shop diagnostic fee
I was about to pay a shop $180 to tell me why my 2006 Corolla was throwing a P0420 code, then a guy at the parts store in Tucson showed me the $20 scanner he keeps in his glovebox. Plugged it in, saw my downstream O2 sensor was reading flat, swapped it for $45 and the light stayed off. Anyone else skipping the shop scan and just reading codes at home?
A $20 scanner reading a P0420 code is one thing, but that code can mean a bad cat too, not just the O2 sensor. You got lucky that the downstream sensor was flat and the swap fixed it, but plenty of people throw parts at that code for months and still fail emissions. The cheap scanner only gives you the code and live data, it doesn't tell you if the cat is actually toast or if you've got an exhaust leak fooling the readings. For basic stuff sure, but don't act like it replaces a real diag on everything.