These two terms are really not codes, at least not diagnostic trouble codes. The 7E8 is an engine data menu. The 7E9 is the same for the transmission.
Can you tell approximately where the knock is coming from? Does it seem to be under the hood or in the vehicle?
Also, is the check engine light staying on when the engine is running? Are you experiencing any engine or transmission issues?
If you are experiencing issues without a check engine light, what I suggest is this. The CAN system needs to be scanned. CAN stands for controller area network. The vehicle has several modules/computers. The CAN connects these components together via a few wires. If you are using a basic scan tool, it cannot read the codes from modules other than the powertrain.
Here is a quick video showing how it's done:
Let me know. Also, if you have other questions, let me know that as well.
Sunday, November 27th, 2022 AT 11:24 PM