1. Welcome to 4Runners.com!

    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 4Runner discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other 4Runner owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

20024runner

Discussion in '3rd Gen 4Runners (1996-2002)' started by Jkpt445, Dec 2, 2021.

  1. Dec 2, 2021 at 11:50 AM
    #1
    Jkpt445

    #1
    Jkpt445 [OP] New Member

    Joined:
    Dec 2, 2021
    Member:
    #24480
    Messages:
    10
    Gender:
    Male
    First Name:
    James
    Vehicle:
    20024 runner
    Hello mew here looking for a little help, I’ve been get 420 error code I’ve replace both 02 sensors repaired an exhaust leak and I can’t even get three cold starts with Che k engine light coming back on
     
    Jkpt445, Dec 2, 2021
    #1
  2. Dec 2, 2021 at 12:10 PM
    #2
    negusm

    #2
    negusm New Member

    Joined:
    Oct 22, 2019
    Member:
    #11745
    Messages:
    2,125
    Gender:
    Male
    Vehicle:
    2002 4Runner SR5 4WD
    Error code P0420?

    Most 2002s uses an AF sensor and NOT an O2 sensor. Go to your TOYOTA dealer and buy the correct sensors by giving them your VIN. The dealer can tell you which combination of sensors you have by your VIN. No one else can.

    If you did replace your sensors with ones from the dealer, the CAT may be bad. Check thermal readings front and back. Back should be hotter if working.
     
    negusm, Dec 2, 2021
    #2
    OverRunner likes this.
  3. Dec 2, 2021 at 12:37 PM
    #3
    Jkpt445

    #3
    Jkpt445 [OP] New Member

    Joined:
    Dec 2, 2021
    Member:
    #24480
    Messages:
    10
    Gender:
    Male
    First Name:
    James
    Vehicle:
    20024 runner
    Thank you
     
    Jkpt445, Dec 2, 2021
    #3
  4. Dec 2, 2021 at 12:38 PM
    #4
    Jkpt445

    #4
    Jkpt445 [OP] New Member

    Joined:
    Dec 2, 2021
    Member:
    #24480
    Messages:
    10
    Gender:
    Male
    First Name:
    James
    Vehicle:
    20024 runner
    Ok what’s the difference between AF sensor and O2 sensor
     
    Jkpt445, Dec 2, 2021
    #4
  5. Dec 2, 2021 at 12:51 PM
    #5
    jester243

    #5
    jester243 rabble rabble rabble

    Joined:
    Jul 13, 2016
    Member:
    #2304
    Messages:
    1,775
    Gender:
    Male
    First Name:
    Dan
    Spokane, WA
    Vehicle:
    2016 4Runner Trail Premium w/ KDSS
    I changed some lights, tires and tinted windows...mind blowing huh
    i found this:

     
    jester243, Dec 2, 2021
    #5
  6. Dec 2, 2021 at 1:58 PM
    #6
    Jkpt445

    #6
    Jkpt445 [OP] New Member

    Joined:
    Dec 2, 2021
    Member:
    #24480
    Messages:
    10
    Gender:
    Male
    First Name:
    James
    Vehicle:
    20024 runner
    Thank you I didn’t know that and once I talked to my mechanic friends a light bulb went off
     
    Jkpt445, Dec 2, 2021
    #6
    jester243 likes this.
  7. Dec 17, 2021 at 6:30 PM
    #7
    Jkpt445

    #7
    Jkpt445 [OP] New Member

    Joined:
    Dec 2, 2021
    Member:
    #24480
    Messages:
    10
    Gender:
    Male
    First Name:
    James
    Vehicle:
    20024 runner
    Hello guys changed AF sensors and a week later threw 420 code again I’m pretty frustrated any ideas
     
    Jkpt445, Dec 17, 2021
    #7
  8. Dec 17, 2021 at 6:35 PM
    #8
    Mtbpsych

    #8
    Mtbpsych New Member

    Joined:
    Dec 3, 2018
    Member:
    #7922
    Messages:
    1,886
    Gender:
    Male
    Vehicle:
    2018 SR5
    What did you change? Your AF/airflow sensor goes on the air intake manifold, and your O2 sensor goes along the exhaust system. If you replaced both sensors you could be having vacuum or EGR related issues.
     
    Mtbpsych, Dec 17, 2021
    #8
  9. Dec 17, 2021 at 6:37 PM
    #9
    Jkpt445

    #9
    Jkpt445 [OP] New Member

    Joined:
    Dec 2, 2021
    Member:
    #24480
    Messages:
    10
    Gender:
    Male
    First Name:
    James
    Vehicle:
    20024 runner
    I replaced both the Front AF sensor and O2 rear sensor on exhaust no one suggested the are AF sensor
     
    Jkpt445, Dec 17, 2021
    #9
  10. Dec 17, 2021 at 7:22 PM
    #10
    negusm

    #10
    negusm New Member

    Joined:
    Oct 22, 2019
    Member:
    #11745
    Messages:
    2,125
    Gender:
    Male
    Vehicle:
    2002 4Runner SR5 4WD
    Not the MAF sensor, we're talking the AF exhaust sensor.

    2001/2002 (depends on the VIN) used different AF sensors instead of the O2 sensors.

    -Mike
     
    negusm, Dec 17, 2021
    #10
  11. Dec 17, 2021 at 7:24 PM
    #11
    negusm

    #11
    negusm New Member

    Joined:
    Oct 22, 2019
    Member:
    #11745
    Messages:
    2,125
    Gender:
    Male
    Vehicle:
    2002 4Runner SR5 4WD
    A few things...

    #1...did you buy from TOYOTA? Chinese sensors do NOT work for LONG.

    #2...did you rule out the catalytic converter? It may be bad. Check the temperature front and back. Make sure the temperature is correct (it should be higher AFTER the Cat Converter)
     
    negusm, Dec 17, 2021
    #11
  12. Dec 18, 2021 at 1:03 AM
    #12
    Jkpt445

    #12
    Jkpt445 [OP] New Member

    Joined:
    Dec 2, 2021
    Member:
    #24480
    Messages:
    10
    Gender:
    Male
    First Name:
    James
    Vehicle:
    20024 runner
    Yes went to Toyota got both front and rear sensors gave vin number to them
     
    Jkpt445, Dec 18, 2021
    #12
  13. Dec 18, 2021 at 1:52 PM
    #13
    negusm

    #13
    negusm New Member

    Joined:
    Oct 22, 2019
    Member:
    #11745
    Messages:
    2,125
    Gender:
    Male
    Vehicle:
    2002 4Runner SR5 4WD
    Sounds like the cat is probably bad then.

    Now...there is a cheap thing you can maybe do to get rid of the code:

    https://www.youtube.com/watch?v=kzm52m0AWSQ

    Worth a try. After doing it, clear the code and pray.

    Also, what are your driving habits? These rigs are notorious to throw that code after highway driving. It happens on mine and I clear the code probably once a year.
     
    negusm, Dec 18, 2021
    #13
  14. Dec 18, 2021 at 4:49 PM
    #14
    Jkpt445

    #14
    Jkpt445 [OP] New Member

    Joined:
    Dec 2, 2021
    Member:
    #24480
    Messages:
    10
    Gender:
    Male
    First Name:
    James
    Vehicle:
    20024 runner
    It’s most likely the cat but I don’t have $900 to replace it I’ve heard about the sensor extend I’ll have to give it a try
     
    Jkpt445, Dec 18, 2021
    #14
  15. Dec 18, 2021 at 8:50 PM
    #15
    negusm

    #15
    negusm New Member

    Joined:
    Oct 22, 2019
    Member:
    #11745
    Messages:
    2,125
    Gender:
    Male
    Vehicle:
    2002 4Runner SR5 4WD
    Did you check the before and after temps of the cat? An infrared thermometer is like $20.

    You should know where the problem really is.
     
    negusm, Dec 18, 2021
    #15
Register FREE to Reply!
To Top