My check engine light just came on with a code of P0401 (EGR insufficient flow). From the error code I have a basic understanding of what the possible issues could be, but my question is that I recently (about a month ago) had some exhaust work done including having a new catalytic converter installed by a mechanic.
Given this recent work are there some possible/probably causes related to the recent exhaust work, e.g. the new catalytic converter was not installed properly, a hose was not securely fastened, etc?
I wasn't planning on returning to the same mechanic again (which I only used once) because of other issues (for example they overinflated my my tires 1-2 psi over the maximum rating of the tires which I didn't catch for 2 weeks). However, if they likely caused this new problem I would rather have them fix it then pay extra somewhere else.