OK, the dealership is either A) trying to rip you off, or B) completely incompetent.
The MAIN UNDERBODY CAT has
no sensors monitoring it, so its failing CANNOT be detected by the computer and set of a Check Engine Light. Therefore, you have no evidence from the dealership that it needs to be replaced. DO NOT AUTHORIZE THEM TO REPLACE IT UNLESS THEY CAN GIVE YOU A GOOD REASON. And by good reason, I mean visual evidence of complete shell corrosion, a vacuum test showing it is clogged, or a failed smog sniffer test. And nothing else.
Next, the DTC (Diagnostic Trouble Code) the dealership got when they scanned the computer will tell them
which exhaust manifold cat (aka precat) was detected to be failing, or both. DEMAND THAT THE DEALSHIP GIVE YOU THE DTC(s) THEY RECEIVED BEFORE AUTHORIZING WORK. Then post them here. We know what to do with them.
However, if you need to replace one or both, it WILL be costly both in parts and labor. I ended up getting a used one and doing it myself, and I struggled with the easy side (near the radiator). I don't think I would ever try the other one alone.
I repeat:
THE MAIN CAT CANNOT BE MONITORED BY THE COMPUTER. THE TROUBLE CODE WILL INDICATE WHICH EXHAUST MANIFOLD CAT NEEDS TO BE REPLACED, OR BOTH.
My advice: Get the DTCs. Tell the dealership to clear the DTCs. If it (Check Engine Light) comes back, GO TO ANOTHER DEALER.
Can you tell (from all the caps and bold) that I hate dealerships that try to rip off unsuspecting customers?
Oh, and one more thing: Replacing the precats requires replacement of the entire maifold. The precat cannot be removed and replaced from the manifold. It can be bashed out, but once removed from the manifold a new one cannot be put back in.
