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  1. #1

    Exclamation check engine light code p0430

    Well this just happened about 2 hours ago well driving. My book says its p0430 three way catalytic converter system low efficiency (bank 2).
    What in the world does that really mean.

    Information for the truck:
    1996 chevy Tahoe LT with 5.7l vortec and 4l60e tranny.
    197,280 miles. Bone stock engine ran only highway miles until I got it at 193,500 miles since then mainly city miles. Recently the truck has been running rough, has poor acceleration/power and sounds like it it missing. Soon I'm replacing the plugs, wires, distributer cap, and fuel filter. Recently the truck had its rear main seal and oil pan gasket replaced. Currently running conventional oil :( with a Fram tough guard filter. Truck sat with no oil for almost three weeks well I was working on it then I had to have it towed to a shop who finished the work.

    This truck is my baby and I want it back to how it was when I bought it.

    1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
    Basic mods: Lights all over, bunch of electrical work, and a couple cooling mods.

    Check out my other mods in My Garage: http://www.gmtruckclub.com/forum/sho...t-Tahoe-4-Door

  2. #2

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    Are you still getting the noise from the passenger side on accel? Bank 2 is the passenger side I believe. With it running rough, I wonder if something is going on with the passengerside cylinders. Stuck valve? Broken valve spring? Collapsed lifter? If I let my 1995 silverado sit for a few weeks it would run like crap for a few miles. A valve was sticking or a lifter was not working. But after it warmed up it would run fine. any way, I found this on another site:
    A code P0430 may mean that one or more of the following has happened:

    • The catalytic converter is no longer functioning properly
    • An oxygen sensor is not reading (functioning) properly
    • There is an exhaust leak


    First, inspect for exhaust leaks.
    Next step is to measure the voltage at the oxygen sensor on Bank 2.

    I would check the voltage of the 02 sensors. But, I would not start throwing new o2 sensors and a cat at it until I figured out why it is running poorly. The miss you have and rough running could actually be causing it to not be burning exhaust correctly, hence your code. Just my $.02. If you get a chance to look at the sensor right after the cat on the right side find the number on it and PM me with it, I may have one in "stock" that I can send you for the cost of shipping. Or look it up on amazon or a place of your choice. I need the AC number should be a number like AFS 72.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3

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    What's funny is I'm fairly sure that's the o2 sensor I just replaced. And yes the noise is coming from the pass side.

  4. #4

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    I would get that code looked at in more detail. It should be capable of doing that to better determine if its the Cat or O2 sensor. Not unheard of for even new O2's to go bad. When they do, the computer has to compensate because it's about Emissions thanks to our wonderfull Govt Regs. No need to replace sensors and it's a Cat or vice-versa. Spend a few bucks and get the full code breakdown before acting.
    '15 Silverado 2500 | Crew Cab 2WD W/T | Duramax |
    (Various Chrome items & Bestop Tonneau...)



  5. #5

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    I pretty much did. I can trouble shoot tomorrow won't take too long. I have the multi meter sitting around just gonna check the voltage like @Pikey said. I'll also inspect the o2 sensor connections because I undid some during my work on the truck and I'm not sure if they all were reconnected. I just hope it warms up because it sucks not having power and heat.

    - - - Updated - - -

    Ok in layman's terms how do you check the o2 sensor because even with being mechanicly inclined I barely understand what my manual wants me to do. Also do you need a digital multi meter?

  6. #6

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    I never got under the truck today. Between the cold, having no power, and volunteering at the local fire house distributing red cross supplies it just never got done. The truck runs like absolute crap after it gets cold and has such little power, but once it's warmed up it has more power back but still sounds like junk.

  7. #7
    Sr. Apprentice
    Join Date
    Nov 2008
    Location
    Endicott, NY
    Posts
    66

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    With OBDII systems they use an O2 sensor behind the cat to see if the cat is working properly. Since you don't have any codes indicating the O2 sensor in front of the cat is performing incorrectly and no misfire codes it looks like the problem is either in the rear O2 sensor or the cat. If the O2 sensor is bad it wouldn't affect the operation of the truck since it doesn't do anything except monitor the output of the cat. If you are getting a noise from the passenger side and the truck isn't running correctly I would suspect the cat before I would suspect the O2 sensor. A cat that has come apart on the inside can make lots of noise and could be partially blocking the exhaust and that will really make an engine run bad.

    Bill

  8. #8

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    Quote Originally Posted by BillD64 View Post
    With OBDII systems they use an O2 sensor behind the cat to see if the cat is working properly. Since you don't have any codes indicating the O2 sensor in front of the cat is performing incorrectly and no misfire codes it looks like the problem is either in the rear O2 sensor or the cat. If the O2 sensor is bad it wouldn't affect the operation of the truck since it doesn't do anything except monitor the output of the cat. If you are getting a noise from the passenger side and the truck isn't running correctly I would suspect the cat before I would suspect the O2 sensor. A cat that has come apart on the inside can make lots of noise and could be partially blocking the exhaust and that will really make an engine run bad.

    Bill
    Thanks for the info @billd64. I just saw that you responded for some reason I got no notification about it...
    I have not had a chance to get under the truck to inspect anything in general, for there was a hurricane (I guess you know that since you're from NY) and it snowed like crazy yesterday and still is on the ground today.

    My biggest problem is on my truck there is no easy way to just check the cats because I have a welded exhaust. Tahoe is still running like junk and I have been unable to order new plugs, wireset, and fuel filter (all are pretty close to needing to be replaced which isn't helping) because of current money issues. From what I can tell my gas milage hasn't dropped really, but that's fairly relative because the truck gets bad mpg city anyway. How can I check the cat without physically removing it?

    - - - Updated - - -

    http://www.gmtruckclub.com/forum/sho...#axzz2BjChnOIf
    That's a link to the original thread with video of how the truck sounds currently. Last night when I was out and about I started up the truck and let it warm up a bit not much tho and it was acting like when I got it but it didn't last. Also the temp has been very erratic going too like 185, then up to 215 then back down again.

    I'm sad that I knocked off one of my driving lights under the bumper because of a chunk of snow/ice I hit last night. Didn't find it any where on the road where I though I lost it so need new one.
    Last edited by Conlan Rose; 11-09-2012 at 01:54 PM.

  9. #9
    Sr. Apprentice
    Join Date
    Nov 2008
    Location
    Endicott, NY
    Posts
    66

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    Quote Originally Posted by Conlan Rose View Post
    Thanks for the info @billd64. I just saw that you responded for some reason I got no notification about it...
    I have not had a chance to get under the truck to inspect anything in general, for there was a hurricane (I guess you know that since you're from NY) and it snowed like crazy yesterday and still is on the ground today.

    My biggest problem is on my truck there is no easy way to just check the cats because I have a welded exhaust. Tahoe is still running like junk and I have been unable to order new plugs, wireset, and fuel filter (all are pretty close to needing to be replaced which isn't helping) because of current money issues. From what I can tell my gas milage hasn't dropped really, but that's fairly relative because the truck gets bad mpg city anyway. How can I check the cat without physically removing it?

    - - - Updated - - -

    http://www.gmtruckclub.com/forum/sho...#axzz2BjChnOIf
    That's a link to the original thread with video of how the truck sounds currently. Last night when I was out and about I started up the truck and let it warm up a bit not much tho and it was acting like when I got it but it didn't last. Also the temp has been very erratic going too like 185, then up to 215 then back down again.

    I'm sad that I knocked off one of my driving lights under the bumper because of a chunk of snow/ice I hit last night. Didn't find it any where on the road where I though I lost it so need new one.
    When I first responded I didn't realize you were having other issues before this. Did you ever get a code or CEL when you were getting the noise or misfiring you mentioned in the other thread? Were the oil leaks fixed after you replaced the rear seal and pan gasket? The old small block chevys would get serious oil leaks around their intake manifolds that would run down the back of the block and sometimes puddle on top of the intake manifold. Once those leaks started sometimes the rest of the seals would fail and you could get coolant leaks into the engine block or intake runners. Thinking about it the first thing to do may be to write down a sequence of what happened. From the point you noticed something wrong, the replacement of gaskets and what you saw when you replaced them and so forth to the end. The summary may give you a fresh insight. That cat could have failed if you have some sort of coolant leak into one of the right side cylinders. The cat runs at temps over a thousand degrees and if you get a sudden release of coolant into the exhaust the sudden cooling of the cat internals could cause it to fail. Last year the engine in my Corvette dropped a valve while I was running on the track. Damage was limited to number 1 cylinder and the cylinder liner was cracked in two locations. Both valves were broken off and there was a clear path from that cylinder into the intake manifold. Coolant was pouring out of both exhausts and flash boiling in the cats which created a lot of steam. The passenger side cat failed about two days after the engine was replaced. The cat failure was due to all the coolant that got dumped into it.

    I don't know how old your cats are but there are a couple of things you can do to check them. Since the code indicates the rear O2 sensor is not responding correctly check the wiring to the sensor to make sure it isn't shorted to anything, broken somewhere or that there isn't a bad connection somewhere in the circuit from it back to the ECM. If the wiring checks out then swap the front and rear sensors on that bank or swap the two rear sensors between the left and right side banks of the engine. If the failure indication moves with the sensor then you know you have a sensor issue if it stays at the same location then you know you have a cat issue. Sometimes cats fail by crumbling internally and if you bump them you can hear the debris rattling inside. When they fail in this mode they can reduce the exhaust flow which would increase back pressure and cause the engine to misfire. However, that should cause another code since everything in front of the point of failure will see exhaust backflow. I had an exhaust get plugged on an Oldsmobile one time and there was exhaust hissing out of the carb.

    Bill

  10. #10

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    Ok let me try to go in order, but I'll keep it basic so it is easy to follow

    1. In July of this year I replace my oil filter adapter gaskets because they were leaking like crazy! After that the truck had no leaking problems.

    1 1/2. Had a code during august that I forgot to get checked but it went away after battery removal and never came back. Came on right after my ABS light came on so I just thought it had to do with that.

    2. In early September my serpentine belt, tensioner, and idler had to be replaced because they were squeaking like crazy, during that time the truck was very sluggish when ever it was squeaking because of slipping on all the pulleys especially the alternator. After the fix no problems for a couple weeks and truck was running great!

    3. Later that month after driving home I let the truck sit running while I got my stuff together and listened to a good song on the radio. After I turned off the truck I stepped out and I could smell the distinct smell of burning oil on the cross over pipe. Checked under the truck and could see it dripping from the torque converter cover.

    4. I didn't have the time nor money to fix the truck yet so I kept on top of my oil level and trying to figure out what might be wrong which is why that thread exists. In total the truck lost over 4 quarts of oil during that time all of course were replaced. This went on for 2 weeks then I had the cash to buy my parts so I did and a nice long Columbus day weekend to work on the truck. The work took way to long and eventually I had the truck Brought to a shop to finish it because I couldn't afford wasting my time any more.

    5. I got the truck back after spending $980 on finishing my work. Driving the truck back home it felt like crap and sounded horrible and did for about two weeks. After those two weeks The truck began to regain power and sounded alittle better. I assumed it was because the truck really needed new plugs which it does or that sitting for about 3 weeks with out any oil might of hurt it. But there isn't an oil leak any more.

    6. Last week on my way home the code popped up and instead of ignoring it I went straight to Auto zone to get it checked came up as P0430 as said in the title I then posted this thread. The truck is sporadic with its performance some days it runs great others it acts like it has a V6.

    Info you might want:
    Factory cats, water pump, and 95% of the engine is factory.
    Tahoe drinks coolant but very slowly.
    Every time I've changed the oil it look amazingly clean and has no particles or metal shaving in it.
    There was a very small amount of sludge on the bottom of the oil pan but I cleaned that out durring the gasket removal and replace.
    Before the repair the truck ran great, a little more sluggish then when I first got it, but not much more.
    The truck was spoiled most of its life being garaged and only driven highway miles. That is until I bought it. Now it sits outside and drive almost only city miles.
    There is a lot of surface rust on the truck but its frame is solid as a rock.
    Tahoe has 197,350 miles about and was very well taken care of. Before I bought her she sat for 6 months because the old owner had blown a brake line and didn't feel like fixing it. During that time most of the rusting and pant damage occurred.
    I helped in bring this truck back from the dead, assisting the owner in jump starting it and getting her to purr back to life, that is what makes me and Tahoe have a very deep bond. The sound of that 350 when it first cranked over still rings in my head, its deep rumble yet subtle sound of power.

    Yah, its annoying not having the truck run like when I bought it. I will try to switch the wires and see what happens. Also I taped on both converter during the repair and I didn't hear anything.

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