2002 Sienna emission/CAT system diagnosis?

[MichaelRS]

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.

 

[KrisZ]

So when you say it hasn’t thrown any codes except the evap, but “still nothing”, what do you mean by that? Still doesn’t pass the inspection?

Unless the inspection actually hooks up to the exhaust pipe and measures exhaust gasses, it should pass the code readiness test.

 

[D60]

Interesting. I'm no help but to theorize that if you're not getting cat efficiency codes, the vehicle believes the cats are working sufficiently and that shouldn't prohibit the monitors from setting. I'd think? But where exactly your problem lies I can't say

 

[D60]

Since I learn everything from Aqua Teen Hunger Force and YT, you've definitely tried this?


He links to a doc from Toyota on Google Drive that claims it covers the '02 Sienna (I looked)

 

[mk378]

Watching the O2 sensor live data would show if they are outputting readings that look like a good cat. Make sure that the ECU is not resetting every time you turn the key off. It needs constant power to keep memory, which is a separate fuse circuit. This would be something to consider if none of the monitors ever set.

 

[kschachn]

What code(s) are you getting?

 

[MichaelRS]

So when you say it hasn’t thrown any codes except the evap, but “still nothing”, what do you mean by that? Still doesn’t pass the inspection?

Unless the inspection actually hooks up to the exhaust pipe and measures exhaust gasses, it should pass the code readiness test.

Well, it does not throw any trouble codes. When hooked up to the OBD it says that the CAT Monitor and the EVAP is incomplete. In California they'll let you slide with the EVAP. So I have no idea what could be wrong that my cat monitor is not setting after thousands of miles

 

[MichaelRS]

What code(s) are you getting?

No trouble codes. Just cat and evap monitors not setting

 

[MichaelRS]

Since I learn everything from Aqua Teen Hunger Force and YT, you've definitely tried this?


He links to a doc from Toyota on Google Drive that claims it covers the '02 Sienna (I looked)

Yes thank you. I have seen that and have done it probably at least twice if not three times

 

[dogememe]

How old is your battery? Have it tested.

 

[kschachn]

No trouble codes. Just cat and evap monitors not setting

Yeah sorry I apologize I didn’t see that in your reply.

My old Sienna never gave a code when the original catalyst was replaced. It had been welded twice at the flex coupling and was finally too rusted to repair again.

Make sure all the other sensors are working properly such as the coolant temperature, that may impact readiness. No pending codes either?

 

[MichaelRS]

How old is your battery? Have it tested.

Well the battery has been replaced since this problem started just because it was time to do that. This has been going on for 2 years. So doing it with the older battery, and then with the current battery was fresh and now the current battery is a little over a year old