Evaluating used 2014, what to check for? e.g., EGR, etc

The only way to truly know the condition of the egr circuit is to investigate the whole circuit.

As for the battery, at 6 years old and good use, you won't find anything there.

Good luck and keep us posted.

 

I would suggest using Techstream and running this test here. Nothing to tear down. It would be more conclusive if we had more data collected, but we've got some, and it appears to be connected to reality in the expected direction.

It won't tell you whether some of the intake manifold passages are more obstructed than others. If you want to check that, removing the IM itself is not so big a job. You might bring a fresh IM gasket; they are rubber and have been reused without incident in a pinch, but Toyota forbids that, and by 103,000 it will be somewhat cooked and a bit flattened, so you'd be taking chances with a vacuum leak.

But then, Carmax might be disinclined to take a car back if you've been poking around taking manifolds off.

 

How would they know that was done?

 

I didn't assume the OP would choose to deceive them.

 

It's relatively easy and unobtrusive to remove just the EGR pipe for inspection. That said, with the miles, I would just assume EGR (and intake) cleaning is in the cards.

 

I'd recommend a good washing and waxing of the car, because in doing so, you would likely notice any body repairs, like from an accident, that you hadn't seen at first glance. Sometimes collision repairs just don't make it into the car's history record (like CarFax).

Also run the VIN just to make sure there are no outstanding recalls.

The car is at a good mileage, not too high, and with you knowing the model's pitfalls (EGR circuit especially), it should have many miles and years ahead of it.