P0430 again and again and again

[992dr]

2007 Tahoe PPV 5.3 w/250k miles

Here it is, the infamous P0430 Catalyst System Efficiency Below Threshold Bank 2

I know I know, it's been posted a million times before. Mine pops up and clears itself quite often. I'll get it read and have them clear it and he says after 30 miles it will op up again. But then it clears itself. Just looking to resolve it once and for all.

I have read so much in regard to getting this resolved but am not sure where I should start. Between the coolant to sensors I'm kinda lost.
Who would've thought the coolant could have something to do with Catalyst system?

Oh and it runs and drives fine, no issues at all.

Thoughts opinions suggestions?
All info is much appreciated
Thanks

 

[OR VietVet]

If the cooling system runs too hot or too cold, it effects the engine temp info to the PCM and that effects the air fuel mixtures while running. The age of tune components will effect, faulty O2 sensors effect this, failing catalytic converters can effect this, exhaust leaks can effect, misfires can effect, wrong fuel can effect....etc.

Does not sound like anything at all has been done except read and clear code and drive it.

By the way, you likely have problems, but just don't feel it YET. Needs these systems diagnosed and not ignored.

 

[992dr]

I appreciate your post and info.
That is why I am posting, trying to beat it before it beats me.

How would I go about finding the problems? Bring it to a dealer/mechanic to hook it up and pinpoint the issue?
If that's possible.

 

[OR VietVet]

Hopefully by now, if you are not experienced enough to do it yourself, you have a qualified shop you can trust. Some of what I said can be shared by you. How old are the plugs and wires? Original O2 sensors? Engine temp not in line with what it should be? Engine temp gauge showing correct temp reading? Catalytic converters back pressure tests are good? Using the right fuel and a good quality brand? Any exhaust leaks?

A qualified tech will print out the step by step diagnostics and go at it and not skip any steps. If all checks out with a detailed readouts and printouts, to back up the findings, then you go a little deeper and go after all those pesky grounds that could be causing problems in these circuit(s).

 

[treehan77]

Send a leaf blower or reversed shop vac up the tailpipe and start spraying soapy water at every exhaust joint. Any tiny leak will blow bubbles, if it has a leak by the cat or 02 sensors, can easily cause this code

 

[992dr]

Hopefully by now, if you are not experienced enough to do it yourself, you have a qualified shop you can trust. Some of what I said can be shared by you. How old are the plugs and wires? Original O2 sensors? Engine temp not in line with what it should be? Engine temp gauge showing correct temp reading? Catalytic converters back pressure tests are good? Using the right fuel and a good quality brand? Any exhaust leaks?

A qualified tech will print out the step by step diagnostics and go at it and not skip any steps. If all checks out with a detailed readouts and printouts, to back up the findings, then you go a little deeper and go after all those pesky grounds that could be causing problems in these circuit(s).

I am experienced to a certain extent but am not in any way with a scanner or tuner. Thankfully, I do have a mechanic I can trust.
Plugs n wires were replaced two weeks ago.
O2 sensors have at least 100k miles and are more than likely original.
Engine temp, good question. I will have to research that.
I have used the same fuel for the past 5.5 years and haven't noticed any difference. I will throw some super in it next fill up though.
I'll check tomorrow for exhaust leaks. I'll give what treehan suggested with the blower to check for leaks.

Send a leaf blower or reversed shop vac up the tailpipe and start spraying soapy water at every exhaust joint. Any tiny leak will blow bubbles, if it has a leak by the cat or 02 sensors, can easily cause this code

Thanks man, appreciate the info/help. I'll give it a whirl tomorrow and post back the results.


Thanks guys, I appreciate the help

 

[OR VietVet]

If I was you, I would do all oxygen sensors and do the research on the engine temp and check for exhaust leaks. If the sensors are original, they are way past their maintenance replacement time. That's right, sensors maintenance. Then see what happens after and save the diag money.

 

[992dr]

If I was you, I would do all oxygen sensors and do the research on the engine temp and check for exhaust leaks. If the sensors are original, they are way past their maintenance replacement time. That's right, sensors maintenance. Then see what happens after and save the diag money.

Thank You OR, I appreciate your time and info.
I will be doing the sensors and exhaust leak tomorrow and researching engine temp stuff and hopefully figuring it out tomorrow as well.
Thanks again

 

[OR VietVet]

Before you do the sensors, make sure your spray the threads down and let sit for a while. Plus, for chriminy sakes, use Genuine GM sensors, AC Delco or Delphi. The rest are very suspect. Even Bosch if I was in a pinch. But never ever ever Dorman.

 

[992dr]

Before you do the sensors, make sure your spray the threads down and let sit for a while. Plus, for chriminy sakes, use Genuine GM sensors, AC Delco or Delphi. The rest are very suspect. Even Bosch if I was in a pinch. But never ever ever Dorman.

Will do
I will only buy Genuine, AC or Delphi. Too many issues in the past with other junk.
Appreciate the heads up

 

[mb1500]

With 250K and everything running fine I bet your cat is going bad. The system is constantly running diagnostics and evaluating the perceived state of the catalyst, which is why the code can come off and on if the cat is still working but not 100%. The cat does not have to be clogged to be below threshold, could have zero affect on performance.

The proper fix is to replace the cat. If you don’t have inspections and aren’t worried about your catalyst performance or the EPA you can take a drilled out to 1/2” spark plug non-fouler and install it in between the rear O2 sensor and the pipe and you won’t get the code anymore.

 

[swathdiver]

Unless there is an air leak in the exhaust on that side, P0430 means what it says, a bad cat. It's not O2 sensors, they have their own codes.

 

[992dr]

With 250K and everything running fine I bet your cat is going bad. The system is constantly running diagnostics and evaluating the perceived state of the catalyst, which is why the code can come off and on if the cat is still working but not 100%. The cat does not have to be clogged to be below threshold, could have zero affect on performance.

The proper fix is to replace the cat. If you don’t have inspections and aren’t worried about your catalyst performance or the EPA you can take a drilled out to 1/2” spark plug non-fouler and install it in between the rear O2 sensor and the pipe and you won’t get the code anymore.

Unless there is an air leak in the exhaust on that side, P0430 means what it says, a bad cat. It's not O2 sensors, they have their own codes.

I appreciate the info fellas,
I have a couple of replacement cats that I was collecting for some future exhaust work. Looks like I'll be doing that sooner than later.

I'll be checking for leaks this morning

Thanks again

 

[992dr]

Just tested for leaks. Used the vacuum method like treehan suggested (thanks for the info). No leaks.

Here's a picture of the down stream and up stream O2 on the passenger side. They certainly look OE.
I think since I'll be replacing my cats I'll just replace the O2 sensors as well.

Question. Since I'll be replacing the cats will I have to have it retuned? I'd think no but, then again it will be a freer flowing cat compared to stock and slightly smaller in size.

I may swing by my mechanic to have him test the cats just to be sure. He's a good guy and will probably do it for nothing. I'll just weld something up for him in return haha.

Thanks again fellas, the info is much appreciated

 

[treehan77]

Dang sorry it wasn’t just an exhaust leak. I fixed a v8 Lexus with a tiny leak and p0430 that the dealer estimated the owner $2300 for new cats and sensors lol.

 

[992dr]

Dang sorry it wasn’t just an exhaust leak. I fixed a v8 Lexus with a tiny leak and p0430 that the dealer estimated the owner $2300 for new cats and sensors lol.

No worries my friend, been welding for 22+ years. This is fun stuff for me, plus I've been wanting to do this for a long time. Now, I'll have to get the show on the road. I'll end up driving my Charger while I do this, want it to be purty haha

 

[swathdiver]

No tune or relearn necessary, it will adjust quick enough. Just remember, new cats can throw a code within the first 50-100 miles as they break in. Perfectly normal, just clear it and keep driving.

Lots of folks say to change the O2 sensors at 100K miles. Mine were not lazy and let them go much much longer. What they did fail to do was calculate my alcohol percentage accurately.

 

[OR VietVet]

No tune or relearn necessary, it will adjust quick enough. Just remember, new cats can throw a code within the first 50-100 miles as they break in. Perfectly normal, just clear it and keep driving.

Lots of folks say to change the O2 sensors at 100K miles. Mine were not lazy and let them go much much longer. What they did fail to do was calculate my alcohol percentage accurately.

That alcohol thing has been an ongoing problem that GM engineers just can't seem to figure out....

 

[91RS]

It needs cats. And don’t get cheap aftermarket ones or you’ll be doing it again.

 

[992dr]

No tune or relearn necessary, it will adjust quick enough. Just remember, new cats can throw a code within the first 50-100 miles as they break in. Perfectly normal, just clear it and keep driving.

Lots of folks say to change the O2 sensors at 100K miles. Mine were not lazy and let them go much much longer. What they did fail to do was calculate my alcohol percentage accurately.

Ok cool, thanks for the heads up.
I'll probably replace them just because I'm at 250k miles and I put 100k on it without replacing them.
I love alcohol, I couldn't tell yah my percentage accurately it certainly fluctuates on a day to day. I can tell you it is high.

That alcohol thing has been an ongoing problem that GM engineers just can't seem to figure out....

Honestly have no idea what you guys are talking about

It needs cats. And don’t get cheap aftermarket ones or you’ll be doing it again.

I have had great luck with Maggy spun metallic cats, used them before with awesome results.
I do have two Magnaflow 59959 ss spun cats and two Kooks 307540 cats to choose from.

Thanks again guys, appreciate the info