Catalytic converter?

Driving from Marylland to South Carolina the engine lost power and die. Towed to repair shop who says engines hot. They tell me engine will run for 20 minutes then die. Sits a while and repeats 20 minute run.

Can I replace the sienna Catalytic Converter myself?
If not how much will it cost to repair.

I am in the process of attempting to replaced a P1135 code in my Sienna. Even though I have read about the two pre- catalytic converter sensor. I only find one of those sensor the one in front which you guys wisely refer as bank 2 sensor 1. It is possible than some model only have one sensor prior to the catalytic convertor. The next oxygen sensor that I find is the one that is located right beneath the passenger seat? Thanks in advance.

There is in fact 3 sensors. The one you can see under the hood is on one side of the engine. There is another on the other side of the engine. Just follow up the exhaust from the rear sensor and right between the engine and the firewall you will see the sensor from under the car. It is hard to get to and very hard to see sometimes but its there

The "check engine" light came up on our minivan. My wife noticed it was running slightly rough that morning and when the light came on, she was right around the corner of a service station we often use. She drove right in. They told her they didn't have the time to check it out right then but it was safe to drive. She drove it home (less than 4 miles) and it stayed in the garage until I took it in two days later for a thorough check. They told me it would take about an hour but it took about 2 and a half hours. I was told it needed a tune up and I scheduled it for the next day. I couldn't wait any longer. It took about half an hour for the mechanic to put it back together and he assured me it was safe to drive. All the way home, it rode horribly rough. It seemed to get worse as it was going on. It was bucking and jumping with acceleration and didn't get above 30-35 mph. At first, I thought it was just cold but half way home, I realized it was getting worse. I called the shop when I got home and the mechanic told me he "didn't put it together completely." My wife brought it back the next day and it drove the same way (maybe worse). She and my children also noticed a heavy fuel odor that she told the mechanic about. They did the repairs they talked about but check engine light came back on after a week. I took it to a Toyota dealer and they told me the catalytic converter is fried. I have done a significant amount of research about this and all of the mechanics I talk to are convinced that between the diagnostic appointment and the repair work, the 8 miles of driving in the poor condition caused the damage to the catalytic converter. They have told me the wires were not placed replaced correctly when they did the diagnostic check and the 8 miles we drove allowed unburned fuel to be dumped into the catalytic converter and that most likely caused the failure. When I told this to the service station, the told me the Electric Control Module would prevent any such damage. Toyota says it will handle minor amounts of fuel but that the driving condition I described would not be prevented from causing damage. Can you help in sorting this out?

I think you misunderstood something. The car only got worse when it warmed up after they did the diagnosis step. Until then, the car was a little rough until it warmed up and then it was fine. In other words, the changes they made when they ran the diagnosis created the situation causing the car to run worse when it was warmed up.

What makes you think the catalytic converter had any damage before they worked on it? Was it the issue of how it ran when it was warmed up?

Thanks again.

Bob

That's the question. What did they do at the diagnostic appointment that caused the car to run so bad and did it cause the damage to the catalytic converter. I'm fairly certain they either crossed wires, as was suggested by one mechanic, or didn't connect the wires correctly in another way.