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Discussion Starter · #1 ·
I have a Prius IV 2013 (Gen 3) with 123k miles. I have a P0A80 Error Code and my story is the following:

On Dec 2015 my car showed up a lot of lights and error messages (a message saying something like: "park your car in a safe place" at that moment I did not know that was a P0A80 code). When I took the car to a hybrid mechanic he told me that it was a P0A80 Error Code. He told me there was a Toyota bulletin establishing that this could be caused by dirtiness in the cooling fan that can impair the ability to cool the off the hybrid battery. He proceeded to clean and reset the code. He told me that if the code shows up again in the future then the issue is the hybrid battery. Sincerely, I did not consider the fan was so dirty, in such at extent that could cause impairment in the fan cooling ability. But, anyways, I just try to follow instructions.

After two weeks the error message showed up again but, in this case, the whole hybrid system was disabled, only the mechanic combustion engine was working all the time. Then, I took it again with the hybrid mechanic and he found again the P0A80 code by hooking up to the car while it was turned on. Also, he said that the module 5 had a voltage of only 12.71V and the nominal should be 14.4V. He just reset the alarm and told me that I have to replace the battery.

I went to another shop and the mechanic established that Gen 3 cars are not like Gen 2 cars. That batteries from Gen 2 hybrids are better designed and can be repaired with a higher successful rate. That, usually, for Gen 3 hybrids the hybrid battery has to be replaced entirely since a cell or module replacement may be only a temporary repair that can just last for a couple of months.

I cannot just believe this and I watched a couple of videos from youtube and proceeded to uncover the hybrid battery to try to repair it. I said, I know about electricity. So, I can do it! I verified the voltage of each battery cell with a multimeter and one cell from module 4 and the two cells of module 5 measured 7.63V, 7.59V and 7.57V respectively. The rest of the cells measured from 7.68V to 7.70V. The cells located closed to the module 5 are different from the rest of the cells (like the mechanic established previously) but the difference is not as significative as the mechanic established 12.71 from module 5 is much less than the sum of both module 5 cells (7.57V + 7.59V = 15.16V). Also the difference from these three modules is just about 0.10V from the rest of the cells. It is because I measured the cells when the car is off?

Another detail is that the mechanic combustion motor (I think it is called the ICE-internal combustion engine) revolutions accelerates at some light stops. The usual behavior is that the car mechanic motor turns off or revolutions are low. I read in some place that an erratic ICE is a sign of faulty hybrid pack.

What should I do? Should I just replace the cells with different voltage? Where can I buy them? Should I trust used cells sold cheap on internet? Or the only option is to replace the entire hybrid pack? Is there another part from the battery pack that I should also test?

Super Moderator
'17 C 4
637 Posts
YOU should not replace any component of the hybrid power system.

If you haven't already, I would first replace the 12 V aux. battery.

After that, shop around your area for shops that specialize in hybrid batteries.
I do NOT think replacing individual cells is the route to the others cells will likely fail soon after.

How did you manage to get so many miles on a 3 year old car ? Taxi cab service ??

And before you spend any money on anything, check and double check the warranty on the hybrid power system.
It might surprise you to find that it is still under warranty.
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