My car is a 2002 Sienna with 239,100 miles on it. I'm in Calif. and a couple of years ago it did not pass smog because my cat monitor would not set.
Over that time everything else (except the Evap monitor, but that doesn't count here) has been fine and it has never thrown any codes related to oxygen sensors or the CAT or anything else. I have driven the appropriate Toyota drive cycle, even a couple of listed alternate ones, and still nothing.
Last month I had my muffler replaced and a donut gasket just before the main CAT.
Unfortunately I'm on a fixed income and cannot afford to just throw money at it to have parts or components replaced willy-nilly in the hope that one or two of them might be the solution to the problem.
So what kind of tests should I expect a mechanic to perform in order to accurately diagnose what might be wrong without him saying well it could be this or that, we'll just have to replace it and see.
In particular how might he diagnose if the CAT itself is bad? The place where I had the muffler and the donut gasket replaced is basically just that; a parts replacement service for such things and the only "diagnosis" they did for my CAT was the tap on it and tell me they didn't hear any rattling.
Over that time everything else (except the Evap monitor, but that doesn't count here) has been fine and it has never thrown any codes related to oxygen sensors or the CAT or anything else. I have driven the appropriate Toyota drive cycle, even a couple of listed alternate ones, and still nothing.
Last month I had my muffler replaced and a donut gasket just before the main CAT.
Unfortunately I'm on a fixed income and cannot afford to just throw money at it to have parts or components replaced willy-nilly in the hope that one or two of them might be the solution to the problem.
So what kind of tests should I expect a mechanic to perform in order to accurately diagnose what might be wrong without him saying well it could be this or that, we'll just have to replace it and see.
In particular how might he diagnose if the CAT itself is bad? The place where I had the muffler and the donut gasket replaced is basically just that; a parts replacement service for such things and the only "diagnosis" they did for my CAT was the tap on it and tell me they didn't hear any rattling.
Last edited by a moderator: