DIY - Correcting the P0430 Code

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by rugerjitsu, Jun 29, 2010.

  1. rugerjitsu

    rugerjitsu New Member

    My truck (97 Silverado Z-71) is due for Inspection here in PA...they do emission testing.

    I've had a CEL illuminated for a few months, so I need to fix the problem prior to Inspection.

    I went by Autozone and had them run the codes for me, and it was P0430 (Bank 2). From the research I've done it looks like it's either the Cat or the O2 Sensor.

    The truck has 178k miles on it, and the Cat's are original equipment. I've changed one or two of the O2 Sensors a few years ago, but i'll be damned if I can't remember which one's I replaced!!

    I understand from reading that you can test the O2 Sensors, but I don't know what tool I need for, please enlighten me! also, wouldn't hurt to explain the procedure for testing if you have the time.

    I'm assuming this should be done first, and after testing, if I find that all O2 Sensors are good, then I should look at replacing the Cat...right?

    Many thanks in advance for your help!

  2. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    A couple of different ideas:

    1) Switch the post cat O2 sensors left to right and see if the code follows the sensor or not. If the code follows the sensor, the sensor/circuit is probably at fault. If the code stays the same, the cat is probably at fault.

    2) If you have a scanner (more than a code reader, you need one that can monitor PID"s), you can monitor the post cat O2 sensor data. Post cat sensors should not have a lot of variation in the reading.
  3. rugerjitsu

    rugerjitsu New Member

    will the code reflect the swapping immediately? in other words, if i swap the o2 sensors after work today, would i be able to test the code immediately afterwards?? and if the code switches to Bank 1, then I know to replace the post cat o2 sensor on Bank 2, correct?
  4. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    It might not show up immediately after the first drive cycle (be sure to clear the code after switching sides). It's been a couple of years since I dealt with this code on mine, but, as I recall, it often took a few drive cycles for the exact set of conditions that trigger the P0420/P0430 codes to occur reliably. It might take a couple of days for the CEL to come back on and set the code.
  5. rugerjitsu

    rugerjitsu New Member

    that may pose a problem for see, i just registered my truck up here in PA, and was notified i had 10 days to get the truck inspected. i'm thinking of going ahead and replacing the post cat bank 2 o2 sensor, and having the code cleared...the shop will probably tell that the codes been cleared and give me a time frame to bring it back in, maybe somewhat of a grace period. ughhh, what a beating...
  6. rugerjitsu

    rugerjitsu New Member

    okay...i'm having major problems just trying to remove the old o2 sensor...the first socket was the long cylinder type, with the slot for the didn't work because of the location of the post cat bank 2 sensor. i then bought a $28 socket, that is short, but has the slot...fits on like a charm, but can't seem to break the damn sensor loose!!!! HELP!!!
  7. wis bang

    wis bang Rockstar 100 Posts

    Run the truck and get the pipe/sensor hot. They are almost impossible to get apart cold...sometimes he threads will 'gall' and strip out when cold IF you can get it to move...

    I've also unplugged the wire and slid it thru a box wrench to break 'em loose when warm...if you have room
  8. rugerjitsu

    rugerjitsu New Member

    Okay, so last night I finally broke the o2 Sensor loose!!! I tried last week two nights, only about 10-15 minutes of actually trying...i used two different o2 sensor sockets, and both failed of them i couldn't even figure out how to use!

    Last night, i tried using a simple adjustable crescent wrench...sprayed the sensor down with some WD-40, and got the engine warm. It finally broke loose, and actually felt like i stripped the damn thing at first! i reached up there, and was able to unscrew it with my hand after the initial break. replaced it with the new o2 sensor, and drove down to autozone to have them erase the code...

    i'll be taking it to get inspected today, so i'm keeping my fingers crossed everything goes smoothly! they said it could fail due to having erased the code so recently, but if so, i'll have a 30 day time limit to bring it back for another emmissions test for free...wish me luck!

    thanks for all the feedback guys...
  9. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    It will almost certainly fail. It takes several drive cycles before all the I/M monitors are complete. Like you say, though, the idea is to get that 30 "extension".

    One thought, if you can get a hold of one, most scanners (maybe not the bottom of the line code readers) can check the I/M monitors and tell you when they are all complete, so you'll know when to take it back in for the re-inspection.
  10. Tony Arms

    Tony Arms Member

    I am so glad I live in a part of Pa. that has no emissions testing.

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