1. Welcome to Tacoma World!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tacoma discussion topics
    • Communicate privately with other Tacoma owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Check Engine Light, Code 'P0420' popped up in my 01 Tacoma

Discussion in '1st Gen. Tacomas (1995-2004)' started by prerunnerSD, Apr 12, 2012.

  1. Apr 12, 2012 at 10:10 AM
    #1
    prerunnerSD

    prerunnerSD [OP] "I Brake for Tailgaters"

    Joined:
    Sep 7, 2009
    Member:
    #22428
    Messages:
    253
    Gender:
    Male
    Northeast USA
    Vehicle:
    01 Tacoma Limited 6 cylinder 4X4
    Grill guard Front and rear Bilstein 5100's Front Coilovers Rear AAL "I Brake for Tailgaters" Firestone Destination A/T (P265/75/R16)
    My 01 Tacoma's check engine light came on yesterday afternoon here in Boston and with a code checker learned it was PO420, "Catalyst system efficiency below threshold Bank 1"

    With my general research I understand its a problem with the catalytic convertor and problem could be a sensor or the entire catalytic convertor...

    Any advise on what I should look for or do and how to ensure a mechanic doesn't fix the wrong thing or suggest a more expensive repair. My truck has 156,000 miles

    Is this a serious issue? Otherwise the truck seems like its been running fine. I've done all the oil changes since I bought it last June but I do think it needs a tuneup too.

    PS How is this issue effecting my truck? Is it effecting fuel economy?

    [​IMG]
     
  2. Apr 12, 2012 at 10:19 AM
    #2
    seksilumpia

    seksilumpia Well-Known Member

    Joined:
    Oct 25, 2009
    Member:
    #24905
    Messages:
    592
    Gender:
    Male
    First Name:
    Brandon
    El Dorado Hills
    Vehicle:
    05 TRD Sport DCSB
    Performance mods: TRD CAI, AFE throttle body spacer, Doug Thorley headers, TRD exhaust. Cosmetic mods: HID 10k head+3k fog lights, BHLM, T-rex 2 eyelids, billet grill (5 piece), 20% front window tint, 4% back window tint, tinted 3rd brake light, altezza tail lights, LED license plate lights, door skid protectors, slotted drilled rotors,plasti dip rims,painted rotor and drums. Interior mods: TRD seat covers, LED map and dome lights, 2 kicker 10' w/ 500 watt amp, pioneer door speakers,and Pioneer AVIC X930BT.
    yes it is a serious issue,i would fix it as soon as possible. Check for exhaust leaks first,then new 02 sensors. Those usually throw a code for a bad cat, and could potentially save you some money if that fixes it. Other than that,youll have an annoying CEL on,losing mpg and creating a head ache for later...im going through this right now...As you can tell,i ignored it since i didnt have to get smogged for another year...now i created problems..good luck!
     
  3. Apr 12, 2012 at 10:26 AM
    #3
    prerunnerSD

    prerunnerSD [OP] "I Brake for Tailgaters"

    Joined:
    Sep 7, 2009
    Member:
    #22428
    Messages:
    253
    Gender:
    Male
    Northeast USA
    Vehicle:
    01 Tacoma Limited 6 cylinder 4X4
    Grill guard Front and rear Bilstein 5100's Front Coilovers Rear AAL "I Brake for Tailgaters" Firestone Destination A/T (P265/75/R16)
    Thank you. How do I check for exhaust leaks and is changing the sensors something I could do myself with reasonable mechanical experience or are these parts not accesable? Btw what is a bad CEL on?
     
  4. Apr 12, 2012 at 10:34 AM
    #4
    crazyengineer

    crazyengineer Well-Known Member

    Joined:
    Feb 10, 2011
    Member:
    #50948
    Messages:
    3,354
    Gender:
    Male
    First Name:
    patrick
    Bristol, TN
    Vehicle:
    05 Tacoma SR5 TRD Offroad
    K&N Cold Air Intake, Warn Winch and Bumper Guard, Wet Okole Seat Covers, Undercover Bed Cover, TRD Kenwood Head Unit, Infiniti Speakers, JL 13.5 inch pancake sub
    I had something similar pop up on my 05

    its been there for a good 6 or 8 months

    I want to fix it but dont have money, my parents are gonna get it fixed for me over the summer.

    basically you can drive it, but it would probably be better to fix it.

    I had mine read at a full shop (where they hooked it up to a laptop or something) rather than just a code reader like they use at auto zoen or something. My catalytic converter had gone bad, which is going to be like 900 bucks. you may want to do that, though it will cost some money.

    I have a CAI in mine and wil be switching to stock to see if that could be it, but still its not good. I was talking to my shop and they said it could very easily drop my MPG by a couple miles or so as well.


    SO, I am interested in this too. especially what you do to fix it. Because if it is just an O2 sensor it will be a lot cheaper


    also, it doesnt matter for inspections near me....I dont have them, I like TN
     
  5. Apr 12, 2012 at 10:38 AM
    #5
    prerunnerSD

    prerunnerSD [OP] "I Brake for Tailgaters"

    Joined:
    Sep 7, 2009
    Member:
    #22428
    Messages:
    253
    Gender:
    Male
    Northeast USA
    Vehicle:
    01 Tacoma Limited 6 cylinder 4X4
    Grill guard Front and rear Bilstein 5100's Front Coilovers Rear AAL "I Brake for Tailgaters" Firestone Destination A/T (P265/75/R16)
    Yes I am def going to fix it asap and get to the bottom of this. This truck is in great shape. Mechanics here marvel at its lack of rust and condition after being over a decade old.. Its orig from San Diego and I want to keep it sharp.
     
  6. Apr 12, 2012 at 10:51 AM
    #6
    SnowroxKT

    SnowroxKT AK SnowroxKT

    Joined:
    Dec 11, 2011
    Member:
    #68604
    Messages:
    3,957
    Gender:
    Male
    First Name:
    Kyle
    Anchorage Alaska
    Vehicle:
    Roxy '95 Manual 4x4
    SAS locked geared
    The Oxygen sensor for the Catalytic Converter IS NOT changing how the truck runs. (hence why O2 sims work for the REAR O2 sensors). The only thing those rear O2 sensors do is tell the computer how well the cat is doing.

    If you have strict vehicle inspections it will probably be best to fix it correctly (Cat or O2 sensor, maybe both) but this is $$$ :eek:

    FWIW you can either find some O2 sims and use those and forget about the cats, or delete the cats (and still deal with the CEL if no O2 sims or trick*), or replace with high flow cats (and might still deal with the CEL if no O2 sims or trick*)

    *trick is to find some spark plug anti-foulers with the same diameter and thread pitch of the O2 sensor. (normally ~3-8 bucks for 2) and drill out one anti-fouler so the O2 sensor fits in without damaging it, and then screw the O2 sensor into the drilled anti-fouler, then then screw those into another anti-fouler, then screw that back into the bung on the exhaust. :cool:

    EDIT: the trick works by moving the O2 sensor out of the "stream" or gasses so it "sees" less bad stuff going by.
    EDIT2: MPG will not change unless the cat is clogged or partially clogged (or anything downstream of the cat is clogged too)
     
  7. Apr 12, 2012 at 11:02 AM
    #7
    crazyengineer

    crazyengineer Well-Known Member

    Joined:
    Feb 10, 2011
    Member:
    #50948
    Messages:
    3,354
    Gender:
    Male
    First Name:
    patrick
    Bristol, TN
    Vehicle:
    05 Tacoma SR5 TRD Offroad
    K&N Cold Air Intake, Warn Winch and Bumper Guard, Wet Okole Seat Covers, Undercover Bed Cover, TRD Kenwood Head Unit, Infiniti Speakers, JL 13.5 inch pancake sub
    ya, mine is rusted. I am looking forward to getting mine fixed and see the MPG change (hopefully)
     
  8. Apr 12, 2012 at 11:37 AM
    #8
    Yamaha Dave

    Yamaha Dave Well-Known Member

    Joined:
    Mar 27, 2010
    Member:
    #34080
    Messages:
    2,677
    Gender:
    Male
    SnowroxKT is right, almost everyone else is wrong. Bank 1one is not the O2 sensor, its an Air Fuel sensor. The A/F sensor will effect your MPG and cause the engine tneceo run less efficient using more fuel than necessary. The A/F runs around $150-$179there at most auto parts stores like Advance and Auto Zone. It's fairly easy to change and can be done with basic hand tools.
     
  9. Apr 12, 2012 at 5:13 PM
    #9
    DNG

    DNG Well-Known Member

    Joined:
    Aug 31, 2011
    Member:
    #62654
    Messages:
    194
    Gender:
    Male
    Orange County, CA
    Vehicle:
    White 01 DC PreRunner
    Clean your MAF sensor. I had the same code a couple months ago. I cleaned my MAF and no more code.

    If you have a K&N air filter, the oils can build up on your MAF. This causes your truck to run rich, which makes your computer think your system is below threshold. Thus, the PO420 code and lower MPG.
     
  10. Apr 13, 2012 at 5:01 AM
    #10
    magog45

    magog45 Well-Known Member

    Joined:
    Dec 1, 2009
    Member:
    #26811
    Messages:
    455
    Gender:
    Male
    Canada, just south of Santa
    Vehicle:
    98 tacoma 4x4 extended cab
    5100's all around, 2 inch lift, polyurethane body mounts, gibson exhaust, variation of the deckplate mod, intake resonators removed
    Before you spend a lot of money check for exhaust leaks and yes clean the MAF sensor, also think back to where you bought your last tank of gas. I had the same code a while back shortly after buying gas at a different place of questionable quality, the code kept coming back til i had used up that tank and after a fresh tank of gas it was gone.
     
  11. Apr 13, 2012 at 9:04 AM
    #11
    Hillingdoner

    Hillingdoner Well-Known Member

    Joined:
    Jan 9, 2012
    Member:
    #70273
    Messages:
    458
    Gender:
    Male
    Rio Rancho, NM
    Vehicle:
    95 LX xtracab 3.4L 4x4 5spd
    140 amp Cadillac alternator, Audio system in progress, 4Runner map light mirror conversion, foot well lamp addition, buckets and console from 99 Tacoma regular cab, big three, tint
    You know, I had this problem too. Filled the tank up. We drove it for a while and tend to try to shift into 5th as soon as we can. Seemed like we were going about 40 in 5th up a slight grade and the light popped on. Same code.

    I had a look on the boards and in the manuals. Exhaust leak seemed the no.1 to look for. Also the cheapest. Then testing/replacing the sensors as a pair with Denso seems to be the norm. Then it seems to be the cat.

    I then read about people saying they had issues with the fuel they bought causing the light. Hate to say "cheap" fuel (as none of it is anymore!), but let's say fuel that maybe has a higher percentage of mix in it. Anyway, I thought why not give it a go so I got a fuel system cleaner. I used that Fuel System Restore in the silver bottle, but the Chevron fuel system cleaner (not injector cleaner) is supposed to be good too. Put that in the tank and the light has stayed off for 3 fill ups (approx 825 miles or so).

    Just filled the tank again and got to about 3/4 tank and the light popped on again.

    I do wonder if we are perhaps lugging the truck a bit by going to 5th so quickly at times (we short shift to try and save fuel) and that combined with the fuel is causing a light. No support for this, just a feeling as I thought I'd read somewhere a post about someone who drives similar and they have the light pop on.

    Anyway, point is you might also try popping a cleaner in the tank and then next time you fill don't go to the same location.

    May end up you need the sensors or a cat, but money is tight so might be worth trying the simple/cheap things first before jumping in to the big dollar stuff.

    On my part, I'm going test my sensors just to see where they read. I might pop a thing of Chevron in just to see what happens.

    Cheers
     
  12. Apr 14, 2012 at 7:34 PM
    #12
    Yamaha Dave

    Yamaha Dave Well-Known Member

    Joined:
    Mar 27, 2010
    Member:
    #34080
    Messages:
    2,677
    Gender:
    Male
    ^Look don't get your panties in wad and quit acting like a woman. Here let me educate you. There is a reason Toyota calls the front sensor an Air Fuel sensor and the rear sensor an O2 sensor with two different part numbers and two different part descriptions. So I guess Toyota is wrong as well then by your definition. The components themselves are similar, but they operate completely different internally from one another with different purposes. So you cannot buy an O2 sensor and use it in place of an A/F sensor, or vice versa. If you're going to talk intelligently about technical issues you need to refer to parts in proper terms in order to give accurate advice.


    :rolleyes:
     
  13. Apr 15, 2012 at 10:06 AM
    #13
    Yamaha Dave

    Yamaha Dave Well-Known Member

    Joined:
    Mar 27, 2010
    Member:
    #34080
    Messages:
    2,677
    Gender:
    Male

    I see you conveniently edited your post and removed the cursing/cussing that you responded with. That's why I told you to get your panties out of a wad, because like a woman you don't know how to have an informed debate without throwing profanity in your response. So NO you did not respond tasteful or respectful, and NO you did not hurt my feelings, it's called being civilized but seeing your from Idaho I can understand why that's hard for you. So now your not only giving wrong information, now your lying. I feel sorry for you and your bitter angry life. (See your quote in under your screen name that tells the whole story). My life is awesome.
     
  14. Apr 15, 2012 at 10:40 AM
    #14
    4wd Boss

    4wd Boss Shake and Bake

    Joined:
    Jan 19, 2012
    Member:
    #70978
    Messages:
    340
    Gender:
    Male
    First Name:
    Jefferson
    Big D
    Vehicle:
    07 4dr 4x4 V6
    Fog Light Mod
    good old fashioned battle in the works.... :popcorn:
     
  15. Apr 15, 2012 at 11:05 AM
    #15
    Yamaha Dave

    Yamaha Dave Well-Known Member

    Joined:
    Mar 27, 2010
    Member:
    #34080
    Messages:
    2,677
    Gender:
    Male
    Tell me where am I wrong. Here let me point out all the FACTS.


    1.) FACT - Toyota labels the sensors differently in all technical writing, diagrams, part numbers, one an A/F sensor, and the other an Oxygen sensor.

    2.) FACT - Toyota has two different part descriptions, both physically look the same, although one has a shorter pig tail harness (about 1ft) and the other a longer pigtail harness (about 3ft).

    3.) FACT - You cannot buy an A/F sensor and replace it with the oxygen sensor or vice versa. The internal construction and objective of each part is different. If these two parts were 100% identical or "the same as you say," then they would be interchangeable. But they're not.

    4.) FACT - Here is a technical bulletin DIRECTLY FROM TOYOTA MOTOR USA specifically stating that while although they do look alike, they are constructed differently with different purposes, EXACTLY as I said above. Google it. So now here is factual data from the Toyota themselves. So if you still want to argue these facts than you'll need to call or write to the Toyota engineers and tell them their wrong too. Have a good day!



    Toyota Motor Sales USA Inc. (Page 6 of 15) "The Air/Fuel sensor is similar to the narrow range oxygen sensor. Though it appears similar to the oxygen sensors, it is constructed differently and has different operating characteristics"




    :cool:
     
  16. Apr 15, 2012 at 12:56 PM
    #16
    Denim Dan

    Denim Dan Confusion

    Joined:
    Aug 22, 2010
    Member:
    #42075
    Messages:
    610
    Gender:
    Male
    First Name:
    Erick
    Visalia Ca
    Vehicle:
    96 4x4 reg cab
    So back on track i have this same problem so it would be best to address the issue it this order?
    -exhaust leak
    -a/f, 02 sensor (putting both cause im not very savy with this part of my truck)
    -cat
     
  17. Apr 15, 2012 at 3:31 PM
    #17
    SnowroxKT

    SnowroxKT AK SnowroxKT

    Joined:
    Dec 11, 2011
    Member:
    #68604
    Messages:
    3,957
    Gender:
    Male
    First Name:
    Kyle
    Anchorage Alaska
    Vehicle:
    Roxy '95 Manual 4x4
    SAS locked geared
    sounds good to me. :thumbsup:
     
  18. Apr 16, 2012 at 4:28 PM
    #18
    04YodaTaco

    04YodaTaco Well-Known Member

    Joined:
    Dec 31, 2008
    Member:
    #12086
    Messages:
    148
    Gender:
    Male
    central NY
    Vehicle:
    04' Tacoma 4x4 base
    New frame mod. 265/75/16 Duratracs.
    Pretty sure this is the code I got from a loose gas cap. I thought it was the sensor too at first. Just throwing it out there as another possible cause.
     
  19. Apr 16, 2012 at 5:29 PM
    #19
    TacoMX

    TacoMX TW's Official anti body-lift pundit

    Joined:
    Aug 24, 2011
    Member:
    #62240
    Messages:
    4,834
    Gender:
    Male
    First Name:
    Jonathan
    Deltona, Florida
    There is a SHIT load of things that can trigger the Po0420 code....

    My problem was an exhaust leak (cracked manifold). Put on a header...and it went away.

    The cat can be bad too.


    And lol @ the internet argument above
     
  20. Apr 16, 2012 at 6:03 PM
    #20
    kingston73

    kingston73 Well-Known Member

    Joined:
    Aug 8, 2009
    Member:
    #20845
    Messages:
    2,453
    Gender:
    Male
    eastern MA
    Vehicle:
    09 SR5 4.0L 4x4
    This is probably the clearest statement of order to check. I got lucky and my CEL was due to an exhaust leak that was fixed with $10 of exhaust tape and sealant. Since you are here in MA you'll definitely need to get it fixed before inspection or it won't pass.
     
To Top