P420 and P430 code after input of new intake manifold

[KDDFordlady]

i am hoping someone else has experienced this problem because I truly feel like I am getting shafted by the mechanics.

Here's the short story---Intake manifold had a coolant leak and needed replacement.
Day one Took to mechanic for replacement and after replacing and updating plugs and coils. Check engine light off. Done. Nope.

Next day back at mechanic's the light is on code is saying EGR tube needs replacement. Fine. Fix it Done. Nope.

Today is day three and the light is back on giving a code P420 and P430 code. Mechanics saying the cat converters need to be replace.readout is Cat is below efficiency on Bank 1 and 2.

Please help because I want to know why these codes didn't show up when first diagnosed and could it really be the cat or are these guys trying to get me to fund their next hunting vacation.

Thanks in advance.

 

[lincolnshibuya]

do you have a check engine light prior to having your intake manifold replaced?

it's suspicious that both cats fail at the same time, they will fail if you have misfires that were not fixed for a long time (killing your cats)

 

[KDDFordlady]

Yes I had the light before but the mechanic said it was from the coolant leaking and causing misfires. Oh and just got the quote for the cat 700 for parts and labor.

 

[lincolnshibuya]

too late then, misfires will eventually kill your cats..