My check engine light stay on 2013 Acadia codes are p0700. And p0496

I had a 2008 Acadia. I purchased it with 102,000 miles on it. at 142,000 miles it started having all kinds of computer singles going off. Finally after having it in the shop a few times they took the Air Sensor off and found that a yellow/watery substance (My ex says sounds like anti freeze) was accumulating in there and they would clear all those 35 computer messages and then a couple weeks later it did the same thing. The mechanic told me that the engine wasn't working like it should which was causing that and he couldn't guarantee me how long my engine was going to last. I only had it a couple years and still owed 11,140 on it. So a good used engine with 60,000 miles on it would be $6,000. Then it had other issues, like a control bar was bad, a bearing going out and need all new tires. The anti lock brake light kept staying on and had a noise on left front tire. All total that would've been another $2,000. He said he couldn't in good conscience tell me to put all that money into it since he didn't know how much longer the engine was going to last. I had to get a 2nd mortgage to pay off the difference the dealer was going to give me of $5,000 and traded for a newer vehicle. No one had anything good to say about the Acadia. I loved my car, but when they hit 100,000 miles the engines are known to go bad. Sorry.