2009 Battery Light, Check Engine, throwing 10+ codes mostly wrong

[Robert Estes]

My son was driving, battery and check engine lights all came on, lost power. He limped it to my mechanic who replaced the alternator. Then runs fine for a short time then same thing happens. He checks all the codes, the system are all ok. Resets, then drives fine, for a bit, then starts all over. Replaced the battery, same thing. Hes stumped. Says its looking like the computer.

 

[Havfun]

I had something that happen a few years ago and traced it down to very corroded battery terminals. Since you've replaced the battery it probably is not causing your problem. I'd check all your battery connections on both sides of both battery cables. For example, a loose screw that connects the ground cable to the frame can cause this. I'd be very dubious about any suggestion to replace the computer. It is far more often replaced than it is at fault. Good luck!

 

[Havfun]

Also, if you see a connection that looks suspicious like some corrosion at a terminal, then put your voltmeter on both sides of the connection while an assistant starts the car. if you see a voltage drop across the connection then you've located the fault.