Toyota Camry '07, Hybrid Battery Failed 2 mo. ago and fault codes show battery failure and catalytic

230k '07 Camry Hybrid starts very rough as though running on one cylinder and severe shudder at same time, also occurs severely when putting in
reverse and slightly when I stop at a light, otherwise runs quite smoothly. Faults codes show hybrid battery failure (it failed 2 mo. ago) and catalytic
converter failure. 1. What could be causing this? 2. Can I get a used hybrid battery? Is this recommended? Dealer wants $3650 to put in a new hybrid
battery. Dealer wants $1650 to put in new catalytic converter.

Used hybrid batteries have unknown life left. Rebuilt ones are put together from the “good” cells of the failed battery pack plus new cells. The “good” cells also have unknown life and can fail in a year. A new pack is best, obviously, but how long do you want to drive the car? It may be time to move on.

What is the code for the catalytic converter? It should be in the form of P0xxx. Some codes point to a cat failure, but it could be a sensor failure. The cost difference is large. Also, $5300 is too much for a car with 230k on it. At least in my opinion. The rough running may be more related to the hybrid failure than the cat failure. A cat failure, like it’s plugged up or collapsed, makes the engine run badly at speed, not idle. You may also need spark plugs and/or a coil or two To solve the rough starting.

Insightful and Busted Knuckles, thanks for the quick responses. Fault code for catalytic is:
PO420 ‘catalytic bank one’. I have always found a great mechanic before I buy a particular
car. Last car before the Camry was a used 70k S-10 Blazer. I put 475k on it and sold it for parts.
Before that a Saab. Got 320k.First car in high school was a VW with 70k. And I simultaneously
bought a great book called How to keep your VW running for EVER. Got 240k on that VW
and only needed to put in five rebuilt engines!
My Camry Hybrid is a great car if treated gently and I repair what my great mechanic and I
AGREE NEEDS TO BE DONE. I NEVER use a dealer’s repair shop. Finding a certified
independent Toyota mechanic is keeping mine running and it looks pristine. My mechanic is
one of the Miller brothers at Miller Brothers in Somerset, Wisconsin.
I have replaced the ignition coils and the plugs and added fuel injector additive to the
gas. I also tried a tank of premium gas. Mileage is even better, but the shuddering continues.
I also found no blown fuses. Consultation with Scott Miller scheduled for Wednesday.
Any other ideas greatly appreciated. Namaste!
By the way, I always get dealer repair quotes, they are among my greatest sources of humor.