How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Chris (aka-Moose) Your Own Question
Chris (aka-Moose)
Chris (aka-Moose), Auto Technician
Category: Toyota
Satisfied Customers: 947
Experience:  16 years of experience
Type Your Toyota Question Here...
Chris (aka-Moose) is online now
A new question is answered every 9 seconds

Ron, I have 2005 Toyota sienna xle, code PO420 cat keep

Customer Question

hi ron, I have 2005 Toyota sienna xle, code PO420 cat keep coming back, I changed all 2 air/fuel sensors, and 2 o2 sensors OEM denso, but code still coming back once in a while, clear it and drive few hundreds miles or thousand mile code come back. smoke car in CA passed with flying color after all monitors complete. I don't want to waste money on the CAT as the smog report show excellent data for HC/CO/NOx, pls give me a help thanks.
Submitted: 1 year ago.
Category: Toyota
Customer: replied 1 year ago.
additional note: my sienna has all complete tune up, new spark plugs , new timing belt new water pump, complete kit all parts are from Toyota runs very smooth but once in a while the CAT code PO 420 coming back....My truly concern is if I buy the CAT OEM from Toyota, will that guarantee the code will never come back or not otherwise is a waste of money and I will go back to square one...remember, smog inspection report in CA passed with flying color HC/CO/NOX are all excellent...
I even tried to use the CATAClean chemical 2 bottles still code coming back in few months....
Expert:  Toyota Service replied 1 year ago.

Hello. Welcome to Just Answer. Please allow me to assist you. Please advise if the Air/fuel and the oxygen sensors were purchased at a Toyota dealership parts department. Thanks

Related Toyota Questions