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P0420 How To Diagnose a Bad Converter

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This topic contains 24 replies, has 14 voices, and was last updated by Dennis Jones Dennis Jones 2 weeks ago.

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  • #486067
    EricTheCarGuy 1
    EricTheCarGuy
    Keymaster

    This is probably one of my favorite videos of 2012 and also my last of 2012. I look forward to your thoughts on this one.

Viewing 9 replies - 16 through 24 (of 24 total)
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  • #577067
    EricTheCarGuy 1
    EricTheCarGuy
    Keymaster

    I don’t think the cause of the failure will make any difference in diagnosis. I don’t believe it really matters HOW it fails, you could still use these methods to diagnose a bad converter. That said, you should address the root cause or your new converter will suffer the same fate as your old one. It is true that you need to address any engine performance issues before you replace a converter. If not, it will be a very expensive lesson.

    Thanks for your input.

    #586854
    John
    John
    Participant

    Hi Eric, in regards to your video about diagnosing a P0420 code, I have the same problem and used a OBD2 scanner to read data from the O2 sensors.

    On bank 1, and revving around 2k RPM, the pre-cat O2 sensor was moving from low to high values back and forth like you said it should be doing, but as far as the post-cat sensor, it was staying around .9V which is quite different from what you had on your scanner for a bad cat. What would this mean in my case?

    Thank you for your time

    #586994
    EricTheCarGuy 1
    EricTheCarGuy
    Keymaster

    [quote=”Wiglud” post=94483]Hi Eric, in regards to your video about diagnosing a P0420 code, I have the same problem and used a OBD2 scanner to read data from the O2 sensors.

    On bank 1, and revving around 2k RPM, the pre-cat O2 sensor was moving from low to high values back and forth like you said it should be doing, but as far as the post-cat sensor, it was staying around .9V which is quite different from what you had on your scanner for a bad cat. What would this mean in my case?

    Thank you for your time[/quote]

    It might mean a bad O2. You might also want to check the temps as shown in the video to verify the catalytic converter operation. If it’s operational, then that could verify an O2 sensor problem. Mostly with a P0420 it’s the catalytic converter and not the O2 sensor that’s at fault.

    #625051
    Brian
    Brian
    Participant

    Any idea how the O2 sensor data would look with a pre-cat exhaust leak?

    My 2004 Subaru legacy has a manifold mismatch due to an engine swap. It’s the California emissions version, so I have three cats and 5 O2 sensors (2 are A/F). I can read OBDII with RomRaider and/or Torque.

    I bought a junkyard header and I’m headed to a muffler shop this week, but I’m hoping it’s not actually the cats. Thanks!

    #625224
    EricTheCarGuy 1
    EricTheCarGuy
    Keymaster

    [quote=”Joeboo25″ post=114169]Any idea how the O2 sensor data would look with a pre-cat exhaust leak?

    My 2004 Subaru legacy has a manifold mismatch due to an engine swap. It’s the California emissions version, so I have three cats and 5 O2 sensors (2 are A/F). I can read OBDII with RomRaider and/or Torque.

    I bought a junkyard header and I’m headed to a muffler shop this week, but I’m hoping it’s not actually the cats. Thanks![/quote]

    You can always check the temperature of the cats to see if they function like in the video. That’s the way we did it before OBDII.

    #625277
    Brian
    Brian
    Participant

    Yeah, I think that’s the next step and I already have an IR thermometer. I’m hoping the manifold swap will normalize my sensor data. But even if it does, I’m still taking the temperature because it’s such a neat test.

    #625401
    EricTheCarGuy 1
    EricTheCarGuy
    Keymaster

    Wait till you see the new toy I got today in action. It will be a bit before I do the review, but when I do, I’ll be headed strait for some cats to try it out on.

    http://www.flir.co.uk/instruments/content/?id=64755

    #987219
    Arfat Anis
    Arfat Anis
    Participant

    My CHECK ENGINE light is ON and I am getting the following error codes on my Ford Explorer 2013 please suggest how to fix them:

    Powertrain Control Module:
    (1) P0420:00-68 Catalyst System Efficiency Less Than Threshold – Bank #1
    (2) P0430:00-EC Catalyst System Efficiency Less Than Threshold – Bank #2
    (3) P2196:0028 O2 Sensor Signal Biased/Stuck Rich – Bank 1, Sensor 1
    (4) P2198:0028 O2 Sensor Signal Biased/Stuck Rich – Bank 2, Sensor 1

    HVAC:
    (1) U0140:00-08 Missing Communication with BCM

    RCM:
    (1) U0557:82-08 Invalid Data Recieved From Front Control Interface Module A

    I will be very thankful to you for your kind help and reply.

    #988048
    Dennis Jones
    Dennis Jones
    Participant

    Hey Eric, thanks for all the help over the years. First time to post here! Did I miss it, or did you ever say which converter on the Odyssey you checked the temperature on? You checked both on the Subaru but only one on the Odyssey so I’m just trying to fully understand. Thanks!

Viewing 9 replies - 16 through 24 (of 24 total)

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