Any thoughts? My 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 mechanic 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). Two days later the CEL came back on while driving, and now the dealer said the Bank 2 Cat is bad (drivers side) and wants $1,800 to fix. There are no rattling sounds coming from the cat, but if the cat was going bad, how did it pass smog two days earlier. Any idea if the real problem is the Carbon buildup the indi thought, or the Cat as the dealer claims?

 

You should ask the dealer to give you a list of all the CEL codes you are getting for you car. Then check if you are also getting a code forthe o2 sensor. A good mechanic once told me that if the o2 sensor is not working properly it will also throw the cat code but not the other way around. If this is the case it is cheaper to replace the o2 sensor than the cat.

I am really not sure about this but probably the cat is just not working as efficiently as it should (the car will still throw theCEL code i guess)and that is why you passed the test but again i am not sure about this.

I wouldn't spend3,000or 1,800 to fix this if it is in fact your cat that needs to be replaced. You have a lot of options...You could buy the direct-fit part online I think you can find them for under 500 and then have an indi shop install it at a cheaper labor rate. Or you could also go with a universal cat ($70) but for this the shop will have to weld the cat.

You can check what the CEL codes mean at this website

http://www.bentleypublishers.com/tec....dtc.table.htm