2002 A6-4.2 Quattro (89,500 miles) has been having a series of CEL / Emissions problems over the past month. The CEL came on and my indi told me that it was related to Carbon buildup on the secondary air injector ports (driver side), and that the only way to fix was a $3,000 engine clean and rebuild. I brought it to the dealer to get a second opinion since I didn’t want to spend 3,000 without any other info. The dealer replaced some hoses and a solenoid for a few hundred and the CEL was gone. Then I got it smogged and it passed perfectly (needed to have this done to register in Ca this month). Two days later the CEL came back on while driving, and now the dealer said the Bank 2 Cat is bad (driversside)and wants $1,800 to fix. There are no rattleing sounds around the cat, so if the cat was going bad, how did it pass smog two days earlier. My question is – is the real problem the Carbon issue the indi thought, or the Cat as the dealer claims?

Thanks -

 

You passed emissions cause after you got your hoses fixed the dealer cleared the faults to the CEL. That's how you were able to pass smog. if the dealership didn't say anything about the Cat fault before then just go ahead and clear the fault.But if the same fault comes back then your Catfor bank2 should be replaced.