I’m 71 years old and changed the cat in my driveway with hand tools. A floor jack and jack stands .

the valve is just a starting point to eliminate suspect parts.

 

A friend is gonna pay the 700$ for the cat. We have one thing accomplished. I will check solenoid. We will get through this thank you all so much for believing in my car and more importantly believing in me. I’m just some wh**e but this is my sad reality the sooner I get this fixed and a new car the sooner I can save up and get myself out the SW industry. WITH TEARS IN MY EYES THANK U ALL.

 

P0449 might be the gas cap is loose or worn out. Could be the fuse. Could be clogged vent valve. Could be leaking vent.

 

I bought a new gas cap from AutoZone is not the gas cap I thought the same thing two birds of a feather, my friend. I bought a fuse tester once and I don’t know how to use it. I was really confused and frustrated so I just returned it.

 

Here a screenshot of the correct fuel cap


Perhaps you purchased another company’s less expensive part, it happens and you don’t save any money

 

ordering now. U r right I played myself.

 

Buy the right part the first time, save time and money of buying it twice!

 

Your Mark V optical sensors can easily and cheaply test fuses. Is the copper conductor broken?

 

Code descriptions lifted from this forum:
P0420 - Catalyst System Low Efficiency
P0449 - Evaporative Emission (EVAP) Vent Solenoid Control Circuit
P0700 - Transmission Control Module (TCM) Requested MIL Illumination
P0751- 1-2 Shift solenoid (SS) Valve Performance - No Second or Third Gear

The problem with events solenoid could just be wiring. It's probably contributing to the problem with the cat. If you fix the P0449 and take it for a long drive, the P0420 may clear up. Good to preserve the original cat if you can.

P0700 is prolly because of the P0751, which is not related to the P0449. Do you really have no 2nd and 3rd gear? Prolly need to replace that solenoid.