[j cAT]

Originally Posted by roblo101

Hello all
Really good forum here, alot of nice reading, thanks.

I have a 96 Chevy ext cab, 5.7 1/2 ton truck. Bought this truck new, been a good truck. In the last 2-3 yrs, changed all 4 O2 sensors, had heads reworked, (intake gasket leaking) had heads done while they were off. An finally had to install fuel pump. 175,000 miles

Have had 1) code PO430 eff below threshold, Bank 2 (cat)

Now have three more, and really poor mileage!

2) PO151 o2 circuit to low, bank 2 sensor 1

3) PO420 eff below threshold, bank 1 (cat)

4) PO131 o2 circuit to low, bank 1 sensor 1

Question is: Should I replace both cats?

And if so, can I use the aftermarket free flow, or what do you advice?
I have a buddy thats a welder, thats no problem.

And does these 2 codes mean the o2 sensors need replaced, or by
replacing the cats, it will help them clear themselvs????????
As high as they are, they should, ha!

Thanks for any an all advice with this, and by the way, it is
original exhuast.
Thanks again
Rob

at this mileage it is common for the cat converter to go .
since you had gasket failures this will also cause these converters to get damaged...

whenever replacing the cat converter the upstream sensors should be replaced as well as any engine componets that could cause an incorrect fuel mixture/ burn condition..your vehicle is at the point where the distributor may be defective as the bearings go at this mileage ..