Toyota Repair: PO0420 and PO1135, toyota seinna, cat converter

Question
2001 Toyota Seinna LE

I have these two codes, PO0420 and PO1135. Just had the car serviced two months ago for timing belt and 70,000 mile service, this is not related to that at all is it? I really would like to go to another dealer. The fix would be for this?
I also have a problem with power sliding door, one power door only.The dealer said it was the ECU and might be the motor also. The door does open and wouldn't close. Power door light stays on always. Where is this ECU located, they wanted $600 to replace it the part is $96 dollars, I'll take my chances on the replacement.

Thanks B Kelly

Answer
The PO420 code is a catalytic converter failure, the PO1135 is an O2 sensor failure(bank 2, sensor one) it's located in the exhaust manifold near the radiator.
The cat converter may still ber covered under the federal emission control warranty(in the US only)which is 8yrs/80,000 miles, have the dealer check for this.
The sliding door problem is fairly common and replacing the door control ECU takes care of it, I have never had to replace a motor, only the ECU. There must be some mistake, the computer is much more than $96.00, the labor should be around $240 plus the cost of the ECU, call the toyota dealer to get an exact quote.