Codes 7E9 and 7E8

These codes are nothing more than your generic scan tool picking up the fact that the PCM and TCM are reporting back that the scan tool requested the codes.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

So, what happens is when you use this scan tool to ask the module to tell what codes are there, the module must send a response to tell the scan tool that it sent the codes. So, this is a message back from the module that is just confirming that the module sent the codes.

Most scan tools ignore this code or just display it as "codes received".

However, if you have only these codes then that is telling you that the PCM and TCM have sent any codes that are there. Which means if there are no other codes then you have no codes in those modules.

See the attached for more details.

Thanks