I did a search.

08 TL-S 5AT

"Engine Sysem: P2647 Engine may not operate properly. Acceleration may be reduced."

It seems most people suggest checking the oil level - did that - it's fine.

The next step appears to be replacing the vtec oil pressure sensor bank 1.

Any other suggestions?

And looking online, I'm not sure which part number it is.

No issues with driving and no issues with vtec engaging.

Strange error for sure.

It seems to come and go randomly.

Here's what I found through google:

https://www.engine-codes.com/p2647_acura.html

 

interesting! never have heard of this problem before!
like you, I searched a bit and came up with the Rocker arm pressure switch.

interesting to note; in one thread, someone suggested changing the oil, as oil can sludge/jell and prevent a rocker arm from moving. but that doesnt sound like the case for you, since you can drive and rev past 4K rpm

 

I already made sure it had an oil change and oil was topped off.

Doing some more digging, it looks like this is the switch:
37250-PR3-003

and the o-ring:
91319-PR3-003

Are there two on these motors, because the code says bank 1...?

Before I swap out the switch, I'd like to know what the switch should ohm out at.

Anybody done their own work on this before?

 

Searching to see if there is a DIY also

 

sorry to steal thread but I have a 07 TL-S AT and I'm having trouble engaging to V-tec I've read that its the V-tec solenoid that I need to replace but I just wanted to see if that's really the issue

 

Check your oil level first.

 

I checked the oil level and its good, I have reasearched that the best thing to do is clean the vtec solenoid and replace the gasket and filter and have a scan tool to erase any codes that pop up