I have an 07 FEH with very low miles. It had 12V battery charging issues in the summer however it works fine in winter. In summer when temperature reached 100F and the A/C is on for about an hour, the 12V battery became 10V and caused lots of issues including break issues. When it happened, there was no check engine light except the check brake light. Scanned but found no code. I'm thinking to sell it but want to fix it before sell it. Just don't want anything bad happen to next owner. Any idea?

 

Start with having the 12 volt battery fully tested. If it is bad or marginal, it can cause a myriad of problems.