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That doesn't sound right. A clogged cat will have too much backpressure, but not sure how it will make the engine run lean... Did the mechanic indicate how he/she decided it was your cat's?
 

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I think you need a different mechanic, that one is going to be very expensive... You need one that can actually diagnose what's wrong, and not just randomly select some expensive part to replace.

And maybe indicate what vehicle/options you have.

If it's a GMT800 or newer, they have O2 sensors after the cat's, to check how well they are working, and wil generate a code if they aren't performing well (but again, I would want to perform additional diagnostics to make sure they really aren't performing right before dropping the money on new cats).
 

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Discussion Starter · #6 ·
I think you need a different mechanic, that one is going to be very expensive... You need one that can actually diagnose what's wrong, and not just randomly select some expensive part to replace.

And maybe indicate what vehicle/options you have.

If it's a GMT800 or newer, they have O2 sensors after the cat's, to check how well they are working, and wil generate a code if they aren't performing well (but again, I would want to perform additional diagnostics to make sure they really aren't performing right before dropping the money on new cats).
I have 05 silverado ls 4.8. But it seems i need more diagnostics done on my truck thanks for the advice
 

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No just off the code on the scanner but i also have the code for the air mass intake sensor
Why not fix the mass airflow first then?

It’s MAF, MAP, then O2s, in that order.
 
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