Error codes

03 4Runner. V8 194k

P2714 lots of youtubers say it’s gas cap. I cleaned out the area and replaced so with OEM. Still with the codes. Can also point to a transmission issue
P0420 O2 sensor. Cat looks really good. Zero rust.
C1201 4x4 diff system ?
C1340 4x4 diff system
If anyone can give some insight into these codes it would be greatly appreciated.

 

Everyone will need lots more information:

Are you the original owner?

Has the O2 sensor(s) ever been replaced? Aftermarket or OEM sensors?

Original factory CAT or aftermarket?

Any recent major maintenance - such as heads or gaskets?

 

Thank you for replying. I do not have all that information. I am #3. Your point is well taken. How about this question: what is the dip stick (red cap) next to the oil dip stick for?

 

There are a lot of really good troubleshooters here on this forum. I do not have specific experience with your model year and engine. But others do.

As for your code P2714, if this pertains to the EVAP system (you talked about the gas cap) then it could be a hose that is old and cracked. There is a lot to look at there.

Regarding the red cap dipstick, someone else will have to answer that.

Others will chime in, you'll see.

 

Thank you. The second dip stick must must be for the transmission. I was distracted by the number of videos referring to a sealed system.