so since the cel is on in my 1998 GMC Suburban and im trying to sell it i pulled the codes. what i got kinda confused me, but it is my first time working with multiple codes.

what i got-

P0102
P0300
P0420
P0430
P0452
P0420
P0452
P0453


The "452" and "420" both came up twice on the code reader, and the "452" and "453" are low voltage at the Fuel tank pressure sensor and then high pressure at the sensor, right? im wanting to know why those codes came up twice, how it could be low and high voltage at the same time, and since its saying that both banks of the exhaust are shot at 181k would it most likely be the o2 sensors or the cats? Thanks for the help!


Edit: im pretty sure that the misfire code was caused by severely worn spark plugs that had at least 80k on them that i replaced, it idles very smooth where before it was rough.

 

reading into it more im thinking that it does need new cats, they rattle a little bit but it has not one, not two, but FOUR cats and FOUR o2 sensors, ill leave it up to the next owner to decide if they want to replace it....

 

to check to see if you need 02 sensors instead of cats you need a scope it should take 100 milliseconds or less for thew 02 to go from rich to lean any longer and it's bad. If you have 100K plus and never changed them you need to anyone or your new ones are doomed for an early grave.