I have a 2007 civic hybrid. The original battery was replaced by the dealer in 2015 at 115,000 miles. The civic now has 170,000 mles. Knowing that the dealer only replaced it with a reconditioned battery i figured id install a grid charging system. The battery was to far gone by this time and i only got me an additional 3000 miles on the battery with the charger. It was recalibrating every day, multiple times and or would get stuck at 2 battery life and the IMA would come on.

I decided to replace the battery. I installed it and everything seemed to be running smooth. The battery was charging the way it should, the car had more power, etc. 129 miles after replacement the IMA light came on again. I got the codes checked and have P15A5 and P0A3F codes popping up now. The codes go away each time I shut off the vehicle but come back on after driving for a little bit. The place i got the battery from told me to check all the connections going to the battery and see if there was a loose connector or wire. I removed the battery and checked all the clips and wires on the side of the pack and reconnected everything.

I reinstalled the battery and now the battery is not even registering. It wont start on the IMA battery, the dashboard shows no charge on the IMA battery, and the IMA light and 12V lights are back on. The battery packs breaker was on. Any clues as to what I am missing here?

 

Those codes are likely completely unrelated to the battery. Pony up for a Honda manual on ebay. There is a fairly extensive diagnostic process for P0A3F which may be the cause of the P15A5.

 

For an average person would it be worth doing this? I did just invest in a new battery, but if the whole sensor needs to be replaced, that's out of my capabilities.
Unlucky timing I guess for this code to pop up.

 

IIRC, the manual is less than $50 for a CD version, and it involves either repairing wires, replacing the sensors or replacing computers that can probably be had from a salvage yard for less than $100