Loose 12 volt Battery Conections causing codes?

Past 6 months I've got Check Engine Lights and went to Advance Auto to use their scan guage that works with the Prius 2004.

The first codes were non-serious upon researching them plus had no symptoms that they are associated and actually just dissapeared after clearing by disconnecting 12 volt battery and waiting 10 minutes to reconnecting.

Although still monitoring for symptoms.

Just yesterday sitting in car (ON) browsing my phone and all of a sudden Red Triangle and Panic
Have a reconditioned battery since 2017 that's been working fine.

The Hybrid fan came on which is rare plus the ambient temp was 64 F
Scanned it and showed Block 4 weak cells Great! P3014
Decided to clear it by disconnecting 12v battery and noticed the battery terminal connection was extremely loose so before reconnecting I tightened it up snug.

I then drove to the beach nearby where speed limit is 25 mph driving up and down the beach to see if there was any severe mileage change after about and hour driving. The long term mileage actually got up to 74.4 mpg which is the best I've ever had for that speed.

The triangle or check engine light never returned and praying it doesn't.
Self Diagnostic on 12V battery looks good

Wonder if anybody else ever experience false positives from a loose battery connection.

Also my electrical system I believe was zapped by a mechanic that had no business working on my Prius a year ago with various electrical anomalies that come and go although not functionally serious.

He had this diagnostic tablet with a big crack accross the screen.

In the mean time looking into the warranty on the battery and getting that app and adapter to check battery blocks and test driving again today at higher speeds.

When the original battery went bad and needed replacing the symptoms like low power and getting worse were loud a clear..

The code yesterday was P3014 Battery Block 4 becomes weak

Plus other ones P0441, P0446, PO455 (leak detected Emmission) I will follow up on those as well

Thanks in advance for you input

Really count on this car as I travel accross the country in my work.

 

Thanks for the responses.

Yes preparing for the worst case scenario.

I did drive again today for a while as well as parked with car on for a long while and everything is working fine.

I did another scan and this time no codes but reactivated my AAA plus membership as a precaution.

Battery warranty runs out soon so looking into that otherwise I'll invest in a newer used Prius as much as I wanted to be the super high mileage Prius Owner. Just 209K now but many thousands of idle time hours as a Prius Camper.

My first and last new car

 

Ok you convinced me! lol

 

So far none of the codes have returned. Praying they don't.

 

Darn! I think I jinxed myself. Same day codes appear P0A80, P3000, C1310 Yikes! Cleared codes but came back in am hour. Looking for good Mobile installers for Southeast NC found a few.

Will look at the fan for blockage of dust and dog hair as read on Prius Chat it may cause a P0A80 hmmm.

This second battery (reman) installed 12/2016

Will go for good reman with warranty as don't plan to keep more than 1-2 years

So far see between $600 - $800 which includes mobile install and warranty options

Hybrid Geek which has pretty great reviews on FB, Google and other places
and another I haven't checked out yet
Hybrid Battery Repair out GA

Will update......

Found this in my searches. Installer installs new hybrid battery in less than 15 minutes Wow!