Which Systems are altered with failing Hybrid Battery

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Here is the workup for DTC P0AFA : https://attachments.priuschat.com/attachment-files/2019/02/161942_2006_Prius_RM_-_DTC_P0AFA_Inspect_Proc.pdf

It should auto-notify you, or you can check this thread for responses, and you can also edit your 'Alerts' settings to email you as well.

Or, if you have a DIY attitude, you could check the ECU and harness for corrosion, then clean or swap as needed.

How many miles on the vehicle, and do you have any interior leaks?

When was the 12v battery last replaced, or what is the measured voltage at the jump points under the hood?

FYI : you posts are being moderated until you've posted five times.

 

Yes, might be. It can be tested.

And MUCH cheaper than tearing into the hybrid battery system.

 

The code you have, P0AFA (the round thing is a zero, not a letter O), indicates a problem with the wiring arranged inside the traction battery to monitor its condition. Those problems aren't uncommon in an older traction battery, and they are not the same as the traction battery failing and needing replacement. (That also can happen, of course, but it hasn't happened to you yet.) Fixing this kind of thing can call only for an inexpensive wiring harness, or at worst a slightly-less-inexpensive ECU. (And well-studied high voltage precautions, to make sure you're around to enjoy the result.)

But are there some untold stories behind your post? Do you have "other odd situations that are" showing up?

 

When talking about car onboard diagnostics, DTC is an often used term, Diagnostic Trouble Code. DTCs are those five-character codes the car gives you, like P0AFA, when you ask it why it has turned warning lights on.

P0AFA tells you about problems with the voltage sensing arrangements inside the traction battery; this is different from the 12 volt auxiliary battery; the traction battery is larger, and runs across the car behind the back seat. It also has a much higher, deadly voltage.

The conditions that get reported as P0AFA can be fairly straightforward to fix. A DIY attitude is a great thing, but for any work inside the traction battery you have to combine it with taking the high voltage hazards seriously and studying how to protect yourself; it's a bigger deal than working on many other parts of the car.

 

Which city and state is the vehicle nearest, maybe there is a member here who can help you.

Here is a glossary thread that can be found in the 'Newbie Forum' sub : PriusChat Glossary | PriusChat

Or a different version in the Gen2 "Main" sub : Acronyms and Abbreviations Glossary | PriusChat

Unless the trusted mechanic is already proficient with hybrids, that link could help identify the problem in a timely fashion.

If you notice excess moisture forming inside the windows after the vehicle sits, or when it rains. You may also find standing water in either of the rear cubbies on the left or right side (which contains the 12v battery) of the trunk, and there may also be water in the spare tire well.

That battery could be getting long in the tooth, though some dealer batteries will last for quite a long time. Replacing with a dealer battery is not be needed (assuming it actually needs replacing), but sometimes you do get what you pay for in terms of quality.

The quoted price is within the ballpark. You might call around to other dealerships and see how much it would cost with or w/o the install.

The diehard product should be just as good as any other random battery. Some will say to avoid the Optima battery. Try to buy the battery with the longest "free" warranty exchange (usually 2 to 5 years), don't fall for just the prorated exchange warranty. Some members have even used a $25 tractor, or a $100 wheel chair battery when money is tight or when looking for a larger amp hour option. Here is a thread that may help : Fitting mobility 12volt AGM battery. | PriusChat

Yes, the 12v battery in the right rear corner of the vehicle (just in front of the rear taillight) is connected to a positive "jumper point" inside a fuse box that is under the front hood of the car (just above the drivers side tire). I'm sure the mechanic can figure it out.

If the vehicle still powers up with the existing 12v (don't see where is hasn't), the mechanics time might be better spent diagnosing the underlying failure for the reported single DTC above (P0AFA). This entails gaining access to the HV battery and inspecting the tiny voltage sense wires, bus bars, and the battery ECU (Electronic Control Unit) socket/connector for corrosion. You can expect 2+ hours for labor depending on the tools and skill level. Once the problem is located, the fix shouldn't take much time to clean up, and if parts are needed, a new sense harness is 60ish and the used ECU is around 100.

There is 'maintenance schedule' in the glove box (or should be), or the dealer could likely print something out. You can also find some of the manuals online, as well as the dealer service history : 2008 Toyota Prius Owners Manual and Warranty - Toyota Owners

Going forward and wanting what's best for your car, do you already know the maintenance history? (dealership or otherwise)

You may want to dive deeper into the forums, or if the curve is too much, post in here : What services you need and what you don't | PriusChat

What is the oil change interval at, and what oil and filter are you using?

Are you buying 'top-tier' gas, or have you ever used an additive with Techron, Regaine, or a similar product before?

There are some big ticket items you can protect by servicing (assuming they haven't been already), you should drain/fill the transaxle fluid, and swap in a new water pump belt, both jobs should take well under an hour. If the coolant in the engine and in the inverter haven't been changed, now would also be a good time. Then you might consider a brake fluid change (might be a gamble), and also having the AC properly serviced by a qualified tech. Would also recommend cleaning up the HV battery fan, especially if you have hippies or furries in the vehicle. The list could go on.. have you already inspected or replaced the cabin filter?

 

You threw several comments after a quote from ME that I had nothing to do with.

A 7 year old 12 V battery is suspect.
I suggest that you let a dealer put in a new one for you and don't fret about trying to save a few pennies.
The prices you quoted seem to be in the reasonable range these days.

 

And he would likely be WRONG......because your car does not even HAVE what either of you think of as a "transmission".

 

Yes.

The screenshot shows the mechanic has misinterpreted the DTC. That's not uncommon, because DTCs have these terse fortune-cookie descriptions listed for them, like "hybrid battery system voltage low", that are pretty much never sufficient by themselves to understand a problem. One has to look the code up in the Repair Manual and find the complete information on what the DTC tells you. Eventually, the fortune cookies might be useful memory jogs for familiar DTCs that you've looked up before, but they're not enough to just run with on their own.

The mechanic figured "voltage low ... oh, the battery has weak cells". But looking up P0AFA in the manual shows that its trigger condition happens to be voltage impossibly low (for a NiMH battery module)—so it isn't saying there are weak cells in the battery, it's saying the built-in sensing circuits can't even tell you about that because they're probably broken.

Response to this sort of battery problem would often be repair of the battery, not replacement. Replacement would probably also make the problem go away, of course, but would be more than is needed.

It's even possible that replacement wouldn't fix this problem, depending on the source of the replacement battery. Some come without the battery ECU, and that's expected to be swapped over. But the battery ECU is one possibility for where this problem could be (if it isn't in the skinny sensing wires of the No. 2 Frame Wire assembly). So if that happened to be the problem and the existing ECU were swapped over, you could find after battery replacement that you still have the problem.

So it would be cheaper and more direct to just check the No. 2 Frame Wire and the ECU, and replace one or both, as necessary.

 

You really need to stay away from any of those recondition places, unless of course, you don't mind your car breaking down every 6 - 18 months, but he is right about needing to drive it for at least an hour 2-3 times a week.

 

... until they have your money, I'll bet.

 

You're only a few hours drive from one our esteemed members - @TMR-JWAP , who could likely help you out in a big way.

The reason for asking is because water may accelerate the corrosion in the HV battery pack. Also being near the salty coastal areas.

Swapping the battery out takes time, some do it for nothing, and others like pepboys/autozone/walmart will charge for install. Call ahead.

Doesn't sound like there is excess water intrusion inside the vehicle, given #1 above.

Excellent. Knowing what has or hasn't been maintained is the first step.

You should be fine without asking, just be sure to check the oil level on a level surface between gas fill-ups.

You will do quite well with 93/E0 from Shell. TOP TIER™ Gasoline Brands

Yes, though dependable gas sippers when being used, they can turn into money pits when left sitting. Seeing as you aren't drving 5-10k+ miles a year, it may be in your best interest to have a conventional vehicle instead.