Bad cat?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

OP
OP
DallasTahoe

DallasTahoe

Full Access Member
Joined
Aug 17, 2012
Posts
711
Reaction score
212
They shouldn't bounce, more like a wave if charted. Replug connectors, Ohm check Sensors, Check wires for wear thru or Pinch spots. Might just be bad O2's. Heater circuit is troublesome, may need to wring out the harness. If cats were gone you likely would have performance issues/missfires.
I say bounce, they were going up and down, but bank 2 wasn’t moving the same as bank 1, And she’s drinking a lot of gas that’s for sure


Sent from my iPhone using Tapatalk
 

exp500

Full Access Member
Joined
May 14, 2017
Posts
1,781
Reaction score
1,609
Being thirsty is the biggest indicator, You need a tune up. Once she loses 2 mpg consistantly it's time.
Minimum is new cap. You could monitor live data to determine how far you want to go on tune up. No history, do it all.
 

east302

Full Access Member
Joined
Dec 21, 2016
Posts
1,557
Reaction score
1,382
Location
Mississippi
Here is the GM diagnostic table for P0430. I thought it might help but it looks like it was written around a Tech2 (step 5).

a02352dca24ba44c80471ad718015224.gif
b4ce9e71e949f86999fc0ccd16610290.jpg
2fcced83a186bc07de9b4d5878a75480.jpg
fa94941bf6c9e0cbc5f86ea71595892d.gif
729befaa5369c6873a45d221c9789ad7.gif


Sent from my iPhone using Tapatalk
 
OP
OP
DallasTahoe

DallasTahoe

Full Access Member
Joined
Aug 17, 2012
Posts
711
Reaction score
212
So finally had time to check it out, had it running and it was rattling, so I tapped on the cats and I could hear something jumping around inside, so definitely bad cats. Now I was going to go with Bosal cats, they got them on rock auto. But I found some through muffler express. They’re cheaper and they give free shipping, but I’ve seen a couple posts about bosal being better than most other brands, anyone know anything?


Sent from my iPhone using Tapatalk
 

BG1988

Full Access Member
Joined
Nov 14, 2018
Posts
2,925
Reaction score
1,329
98 Yukon 4wd, keep getting code p0430, says catalyst system below efficiency threshold bank 2. Would that be the catalytic converter? I replaced all the o2 sensors a couple years ago just as basic maintenance. Thoughts?


Sent from my iPhone using Tapatalk
it's not the CAT you need to have P0420 and P0430 code (4 codes) I had both these codes on and off my self and was able to pass smog without issue.. turned out to be a faulty spark plug and baro for me... the ceramic blew it self apart (the spark plug tip)

if the temp is over 400-700C then they're working ok over that you might be misfiring aka fuel dump or your very high RPM...


check the spark plugs cold engine...


I would check out the MAF sensor this is a typical issue on the older ones i.e GMT800
 
Last edited:

PatDTN

Full Access Member
Joined
Jul 5, 2016
Posts
583
Reaction score
393
I'll toss my experience in here. My cats collapsed completely blocking my exhaust. Right before that I got the same error.
 
OP
OP
DallasTahoe

DallasTahoe

Full Access Member
Joined
Aug 17, 2012
Posts
711
Reaction score
212
it's not the CAT you need to have P0420 and P0430 code (4 codes) I had both these codes on and off my self and was able to pass smog without issue.. turned out to be a faulty spark plug and baro for me... the ceramic blew it self apart (the spark plug tip)

if the temp is over 400-700C then they're working ok over that you might be misfiring aka fuel dump or your very high RPM...


check the spark plugs cold engine...


I would check out the MAF sensor this is a typical issue on the older ones i.e GMT800
The cats are bad, I can hear stuff moving around on the inside when I tap on them


Sent from my iPhone using Tapatalk
 

BG1988

Full Access Member
Joined
Nov 14, 2018
Posts
2,925
Reaction score
1,329
The cats are bad, I can hear stuff moving around on the inside when I tap on them


Sent from my iPhone using Tapatalk
what is the temperature?

if you really think it is the CAT

check out the
Aftermarket Catalytic Converter Database It will tell you which ones that work perfect for your SUV...


I suggest a "Walker" cat that is what i used on my old car . and it worked perfect as well had it for 4 years tell i sold it.. Don't let them steal your old cats though you can get a lot of money on ebay for them...
 
Last edited:

Forum statistics

Threads
128,800
Posts
1,805,626
Members
91,784
Latest member
navyboy14094
Top