Club Scion tC

Guest Menu
Forum Utilities
More Maintenance & Repair Threads
Viewing Thread

P0420 Catalyst system efficiency below threshold- blank 1

  • 12 posts
  • Page 1 of 1
  • 1
    • Dec 30, 2010 1:03:05 pm
    I just took the car to AutoZone and i found out that---P0420 Catalyst system efficiency below threshold- blank 1.

    probable cause:
    *air leak in exhaust before rear HO2S ( Heated oxygen senson) bank 1
    *AF sensor error
    *Fuel system fault
    *Faulty catalytic converter

    Any ideas how to fix them.
    • Dec 30, 2010 1:40:05 pm
    I have the exact CEL code currently...

    I so far replaced the O2 Sensor next to the Rear CAT....That didint work.

    Going to install New O2 Sensor on the Exhaust Manifold tomorrow to see if that will rid the code!.

    My friend says theres a chance the Exhaust Manifold went bad...Might need a New one!...(hopefully not)
    • Dec 30, 2010 3:51:25 pm
    check all of your vacuum and air intake hoses for leaks and cracks. I would also check for an exhaust leak.
    • Dec 30, 2010 8:29:09 pm
    9 out of 10 times when you get this code the catalytic converter is bad therefore you have to replace the exhaust manifold on the vehicle. To check for this you need to moniter the 2 o2 sensors while driving it ( scoping the 02 sensors ).
    • Dec 31, 2010 2:19:15 am
    HPSCIONtc wrote:
    9 out of 10 times when you get this code the catalytic converter is bad therefore you have to replace the exhaust manifold on the vehicle. To check for this you need to moniter the 2 o2 sensors while driving it ( scoping the 02 sensors ).


    Yup...CAT or rear O2 and if the rear O2 didn't fix the issue, most likely the CAT was bad to start with. Changing the CAT now can prevent further damage to the new rear O2 as well. A front O2 sensor will not solve this issue.
    • Jan 10, 2011 7:05:08 pm
    i have the same issue p0420
    still trying to figure it out how to fix it....
    need to check for licks and sensors first , i dont think its a cat cause cat is made to actually work for entire car life and its only 93k miles so far ....
    if you had fixed that problem please pm me !!!! that check engine light is really pissing me off !!!!( and i dont want to spend alot of money, espessialy if its something stupid like really small crack at the pipe...
    sigh stupid computer,doesnt give me time to relax
    • Jan 10, 2011 7:07:34 pm
    I found out its the Exhaust Manifold (Header) thats bad on mine. I replaced both O2 Sensors.

    U can only get it through a Dealership too.

    mikakosha wrote:
    i have the same issue p0420
    still trying to figure it out how to fix it....
    need to check for licks and sensors first , i dont think its a cat cause cat is made to actually work for entire car life and its only 93k miles so far ....
    if you had fixed that problem please pm me !!!! that check engine light is really pissing me off !!!!( and i dont want to spend alot of money, espessialy if its something stupid like really small crack at the pipe...
    sigh stupid computer,doesnt give me time to relax
    • Jan 10, 2011 7:25:12 pm
    If the cat is bad... buy a header and get the "L" shaped CEL fix.. and call it a day.


    FYI I have noticed that the p0420 code seems to show up more with our cars in the winter then in the summer months.... I am honestly unsure as to the why on this.. but I am certain of this event, spread across 5-8 different tC and xB2 owners that I know and associate with.
    • Jan 10, 2011 7:38:00 pm
    • Edited 4 times, last by GtotheJ on Jan 10, 2011 7:39:56pm.
    mikakosha wrote:
    i dont think its a cat cause cat is made to actually work for entire car life and its only 93k miles so far ....

    cats are warranted by the dealer for 8yrs/80,000 miles (whichever comes first) by federal law. so technically its not made to last the life of the car.

    and i have changed many cats because they clogged or went bad, some even well under 80,000 miles.
    • Jan 13, 2011 5:45:12 pm
    well i guess it looks like i have to replace freaking cat , that is not cheap !!!
    well before i do that i made a decision ...i have a friend of mine who is mech and he did some cleaning with his special secret liquid that he doesnt even show the name on it to anyone, alot of shit came out of pipe and a tone of smoke, then we erase the code and he told me that its gonna be ok now for 95% he is positive... well we will c, i give it a try 150 miles, usually after that time light pops up again... if that will not work i guess i will need to find good place where personal does good job on replacing cat for not a big amount of money, because i dont have a lot right now...
    p.s. honestly i would just cut that cat off if that would solve the problem lol but then i would have engine light on that there is not cat ... so i think only one way to go is to replace it ...
    • Jan 13, 2011 7:50:26 pm
    mikakosha wrote:
    well i guess it looks like i have to replace freaking cat , that is not cheap !!!
    well before i do that i made a decision ...i have a friend of mine who is mech and he did some cleaning with his special secret liquid that he doesnt even show the name on it to anyone, alot of shit came out of pipe and a tone of smoke, then we erase the code and he told me that its gonna be ok now for 95% he is positive... well we will c, i give it a try 150 miles, usually after that time light pops up again... if that will not work i guess i will need to find good place where personal does good job on replacing cat for not a big amount of money, because i dont have a lot right now...
    p.s. honestly i would just cut that cat off if that would solve the problem lol but then i would have engine light on that there is not cat ... so i think only one way to go is to replace it ...
    smoke from the tailpipe? sounds like seafoam or something like it.
    • Jan 14, 2011 2:46:48 am
    • Edited 1 times, last by Web on Jan 14, 2011 2:47:49am.
    Yeah, Seafoam, B44K or any other injector cleaner he sucked into the manifold directly. That's not going to clean a CAT if it's clogged. That's only going to add more particulate carbon matter down into the CAT due to the fact that an engine will never burn 100% of it's fuel in the chambers. There will always be residual material and it flows through the mesh in the CAT and clogs up.
  • 12 posts
  • Page 1 of 1
  • 1
Jump to Forum:
Related Threads
Threads
Replies
Views
Last Post
©2014 Club Scion tC - Social Network for Scion enthusiasts.