If only one cell has failed, why do I have to replace the whole pack?

While that seems like a good question, when one understands how these things work and what happens to them over time and what’s entailed in ensuring a healthy pack, the question answers itself - because a game of whack-a-mole is only fun in an arcade - not inside a hybrid battery.

Let me present you with an analogy: You have an 18 wheeler with 18 bald tires. One has blown out. You take it to a truck stop, but before you do, you put covers over the other 17 tires, so they can’t see anything but the valve stem. They replace the blown tire with a used one, and they confirm the pressure is good on the other 17 tires.

What do you think will happen with one of the 17 bald tires? Yeah, one of them is going to blow soon.

Let’s break it down a little. Why did I do something silly like covering the tires? It’s to illustrate the point that the truck stop can’t even inspect the health of the tire tread or sidewalls for cracking - because those tell you something about the health of the tire. The only thing you can check is the tire pressure - which tells you nothing about the health of the tire - much like voltage tells you almost nothing about the health of a cell (a very low voltage can tell you a cell has failed, but a good voltage reading can’t tell you all cells are good).

Let’s say in 3-6 months, when you have a different tire blow, would you take it back to the truck stop and expect them to replace that tire for free because they checked the pressure (voltage) of the tire, but they weren’t allowed to assess the health of the tire? Of course not.

What you can’t see with a voltage check is the state of health of each module. At the time of a cell failure, the majority of the cells in the battery pack have deteriorated to 30-40% of their rated capacity (we’ve seen them as low at 20%). At this level, their cycle wear accelerates and failure occurs more frequently. When you replace a module, you have 20+ other modules with dramatically reduced capacity and reduced life. The reconditioning process restores the cells to their highest potential state of health expanding the available capacity and minimizing cell damage due to cycling.

From pull-up to drive-away, just replacing a module and maintaining an acceptable level of workmanship is going to require 3-4 hours of labor plus parts, and that’s without ANY diagnostics beyond checking voltages. Even at rock bottom shop rates, you’re looking at $300-350, and you’re looking at that EVERY time a module needs to be replaced… every 3-6 months.

Here at Phoenix Hybrid Batteries, we have 10-12 hours of touch-time wrapped up into testing and reconditioning each battery over a 3-5 week period. We’ve invested several thousand dollars in CUSTOM equipment that yields far superior results when compared to commercial options that cost many times as much (e.g., NuVant). We replace an average of 5-6 modules on every pack because they don’t meet our standards. THAT is what it takes to properly test and confirm a pack is as healthy as possible.

If it’s not worth doing right, it’s not worth doing. We’ve turned away many thousands of dollars of “module replacement” business over the years, and we don’t regret a single penny of it.

Many have presented an argument that they just want to get the car running, so they can sell it. Well, that’s just passing the buck. We won’t take part in screwing the next guy down the line.

If the above hasn’t answered your question, please give us a call or shoot us an email.

Thanks for reading!


Because your combination meter (speedo) has failed.  Here's how to turn it off:

  1. Place the car in Park
  2. Insert the fob into the slot
  3. press and hold the power button for several seconds until the car turns off.  When you can remove the fob, you know the car is off.

The combination meter is the unit that displays your speed, fuel level, etc.  It also controls ALL the dash lights except the check engine light. It is something of a computer as it passes data between the other computers.

The reason your car won't turn off is because your car doesn't know it's stopped.  When the combination meter fails, the car no longer has any speed data, so it won't allow you to turn it off in the normal manner.

These failures are very common and were covered under an extended warranty program that has expired for most if not all years (2009 might be covered).

They rarely fail outright and are intermittent in nature. You may have it fail once, and then it works fine for months.  That's what happened in our case.  Our 2008 failed several times in one week.  It then worked almost trouble free for 10 months.  After 10 months, it almost never worked.  We finally replaced it.

It should be replaced as soon as possible to avoid 1) potentially running out of gas because you can't see the fuel level and 2) it's like disconnecting your odometer - it no longer logs miles.

Lastly, if you are a battery customer, it could void your warranty.  Running out of gas can destroy a hybrid battery due to running it empty, and that's regarded as "abuse or misuse" and violates the terms of the warranty.

The dealers charge $900.  We charge $275, or you can DIY by ordering it from Texas Hybrid Batteries.

What's up with my 2008 and the P0AA6 Code?

We collaborate with other organizations doing similar work in other regions. We have received more P0AA6 than other regions by a factor of 4.  The problem is MUCH more common on the 2008 model year accounting for 80% of them.

We have concluded that a manufacturing defect for the 2008 model year exists where some have a tendency to leak more often than others in the harsh Phoenix heat.

One of our few warranty claims has come from a pack that was taken out of service for a P0AA6 code.  The offending module was replaced, and the pack was reconditioned with other replacements made due to performance.  This pack tested exceptionally well and was installed in a new customer's car. The pack performed fine for 5 months until it triggered a P0AA6.

Subsequent to that failure, we took in another 2008 pack with a P0AA6. After testing, the pack developed 4 more leaking modules.

This business only works because we are able to take customer failed core batteries, recondition them and supply them to future customers.  We have made a decision to NOT put 2008 P0AA6 packs back into circulation. As a result, if you have a 2008 with a P0AA6, your pack will be disposed of, and you will be charged a $600 core fee. We will still collect your battery in order to take it out of circulation. It will be turned into Toyota for recycling.

Simply put, if a customer core battery is not usable for future customers, we take a complete loss on the installation of a reconditioned pack.  This happens from time to time and is the nature of the business. While that can't be predicted, a P0AA6 leak on a 2008 can - it's a death sentence for a pack. We don't have a magical source for packs. If you've looked around, packs from salvage yards cost about $1000.  That's about what we pay for the packs we use as sources for modules we replace in the reconditioning process.

Should you choose to purchase a NEW battery, there will be no core charge as it's going straight to Toyota.

We apologize for this inconvenience.


I have the red triangle, and my car won't start

There are only a handful of codes that will prevent you from starting your car.  The most common is a P0AA6 - HV Leak (assuming you haven’t run out of gas!).  This means that some part of the insulation between the high voltage system is "leaking" voltage to car ground (chassis). It is typically in:

  • Battery

  • Harness

  • Transaxle

  • Inverter

  • A/C compressor

Unfortunately, unless you have a code reader on-site, getting codes read on a Prius that won't move is impossible.  Your best solution is to disconnect the 12V battery to clear the codes as follows:

  1. Remove the mat

  2. Remove the cargo tray cover

  3. Remove black plastic cargo tray

  4. Remove cover over 12V battery in the passenger rear corner

  5. Remove purple (maroon?) plastic covering battery terminal.

  6. Disconnect the center of the three connectors.

  7. Leave it disconnected for 2 minutes - don't close the hatch!

  8. Reconnect it.

  9. Replace black tray, cover and mat, but leave the covers that had been on the 12V off for access - this way you can just open the hatch and disconnect the 12V if needed.

This first minute of this video shows steps 1-4 above.


For step 5:

For step 6, user your finger to hook the underside of it, remove this plug:

After connecting the 12V, you may attempt to get the car in ready mode; however, it's a little finicky after the 12V has been disconnected.  Do it as you usually would, but you may need to press it 2-3 times about a second apart.

This will allow you to start and drive the car 99% of the time. If you don't succeed on the first try, and the warning light returns immediately, please try 2-3 more times ensuring you are leaving it DISconnected for at least 2 minutes, as it really is 99% successful. The #1 mistake is not leaving the 12V disconnected long enough. The #2 mistake is not pressing the ON button 2-3 times, 1 time/second until the car goes ready.

Once you are able to get the car started, drive it normally until the light comes on. Once the light comes on, drive STRAIGHT to O'ReillyDO NOT TURN THE CAR OFF.  Keep the car in ready mode and ask them to check the codes for you.  Get the CODE(S).  Don't let them tell you the description. I recommend O'Reilly because they use Bosch code readers that are usually very successful in reading codes that others won't.

If it's a P0AA6, you can continue to drive the car that way by disconnecting the 12V and reconnecting. It's a hassle, but it's the difference between being inoperative and mobile. Toyota disabled the car for a reason, so there is a legitimate safety concern, but I would personally never choose being stranded over being able to return home or to the shop.

A recent customer drove his car for several weeks before correctly diagnosing the code and coming to see me.  He used a hand-held OBDII reader to clear codes rather than resetting the 12V above.

It is important to diagnose the issue in short order.  As noted above P0AA6 can be triggered by many causes. Typically only the dealer (or Phoenix Hybrid Batteries) can read the sub-codes that point to the different potential causes.

The dealer typically charges more than their normal fee for this code due to the far more involved diagnostic process. I can either exclude or confirm that it's in the battery in about 5 minutes.


My battery is BARELY out of warranty. Why won't Toyota cover it?

Well, if the dealer is telling you that, it's because they likely make a little less money on a warranty and aren't motivated to go out of their way to help you.  That is not fact.  It's speculation on my part.  What does seem factual is that MOST dealers or at least the first-contact service people aren't interested in providing value for the customer.

As much as I enjoy reconditioning batteries and providing value for customers, I can't sit here and tell you my reconditions are as good as a brand-spanking new battery from Toyota. To that end, a new battery... under warranty or a "goodwill warranty" from Toyota may be your best value.

If your car is only slightly out of the 8 year/100,000 mile warranty in AZ, then you might get some consideration from Toyota Corporate, particularly if you are the original owner and are only over one of the criteria.  Still inside 8 years, but only 105K miles?  Only 4 months out of warranty, but 90K miles?  A little out on both?

It's worth a call!

800-331-4331, option 4

Things that will work to your advantage:

  1. Original owner
  2. Car has had other problems that haven't been covered
  3. "We are a Toyota family"

Be polite, be respectful, but be insistent.  I have had two potential customers get new batteries for less than $1500.  Well, technically, they aren't my customers, but I helped them get the best value available to them. :)

EDIT:  Yet another!  You can read his account in our Google Reviews!

Do You Work on Other Hybrids?

Here at Phoenix Hybrid Batteries, we have five hybrids.  It runs in our blood.  In addition to the Gen2 Prius, we have a Gen1 running a conversion pack (Gen2 modules installed), a 2nd Generation Honda Civic Hybrid and two of the 1st generation Honda Insights.

While Our principal focus is the 2004-2009 Toyota Prius, we can also work on other models.


We do not stock 2007-2009 Camry packs, and the few we've evaluated have shown substantial deterioration. It appears the Camry is VERY hard on its battery, and reconditioning at the higher mileages is a losing proposition. We can provide you with options including a new pack for FAR less than the dealer charges.  If you locate a battery, we will install it for $200.


We do not work on Altima packs. They are essentially the same as a Camry pack, and they are just as hard on them. They eat them. We had the opportunity to test one, and it was severely degraded with essentially no response to reconditioning. We can't offer new packs either because Nissan is incredibly proud of their packs (made by Toyota).  If you locate a battery, we will install it for $200.

Lexus GS 450h

This is a tough one. The GS 450h has an overheating problem.  If your pack has been replaced and the HV ECU updated, then there should be no issue.  If your HV ECU has not been updated and you get the overheat code, P0A7F, your battery is cooked, and rebuilding or reconditioning is not an option as your pack is effectively destroyed. The modules have been damaged by the heat, and they are only suitable for recycling.

We can conduct an in-depth evaluation.  Due to the time and labor involved, there is a non-refundable charge of $400.  This entails making an assessment of all 40 modules in your pack.  IF we determine that we can rebuild your pack, the $400 is applied towards the cost of reconditioning, and you only pay the price below. If your core is not recoverable, we will not be able to help you.

If we determine we can rebuild your pack, we do not stock Lexus packs, but we can rebuild it with matched modules at our shop and install 2-3 days later for $2,200 with 12 month repair warranty.


Unfortunately, reliable used sticks that perform well after reconditioning are in short supply for the Honda hybrid systems.  New sticks can be purchased from Chinese suppliers; however, they have different characteristics and don't function optimally when paired with original Honda sticks.  However, when a pack is built from all new Chinese made sticks with the proper Quality Control in place, they can perform better than the Honda sticks.

We install Bumblebee Batteries when it comes time to replace your Honda hybrid battery pack. We have complete confidence in their incoming quality testing, sorting and matching process.  It is second to none.  They build a high quality pack at a very reasonable price and stand behind their product. You can't go wrong with Bumblebee's 36 month warranty.

If you can tolerate their wait, Bumblebee is the only organization that builds quality reconditioned packs for a reasonable price with a 12 month warranty.

For marginal packs, we can install the Hybrid Automotive Prolong Reconditioning Package. We charge their retail price plus tax and a small installation fee, but you save on shipping. This will give you a tool to do your own battery maintenance.  The Honda hybrid community has been grid charging their Honda hybrid batteries for several years with great success.  However, there are no guarantees that this will work with your pack.

Note that any price or service referenced may change at any time without notice


Why did my battery fail?

The most common failure is extreme imbalance that eventually drives a cell to failure.  There are 168 individual cells in your Prius.  These are contained in 28 modules with six cells each.  They all respond slightly differently to use and age.  Eventually, they get out of sync with one another until they no longer function well together, and one or more cells fails catastrophically. 

Additionally, while a robust design, there is somewhat uneven cooling within the pack.  The modules in the middle that are surrounded by a large mass of modules on either side, tend to lose their capacity more quickly than the modules towards the ends of the packs.

Here at Phoenix Hybrid Batteries, we have developed a process that reconditions the individual modules and restores them to near optimal conditions.  We're not going to tell you some number like 90-95% of their new capacity because that is very misleading. Those numbers are achieved with very low currents when compared to what they see in the car. To ensure the best results, we use very high current in our testing - representative of the currents the modules experience in the car.  Brand new modules won't meet 90-95% of their new capacity in our tests. There are several other pass/fail criteria that determine if a module is suitable for use.  On most packs, we find that about 20-25% of the modules within the pack do not perform well with their pack-mates for a variety of reasons. This is not because they are bad, but it is because they are not well matched/balanced.

This disparity is why reconditioning a pack with simple module replacement has shorter lived results than a completely matched and balanced pack.  We utilize strict criteria to ensure all modules perform optimally with their pack-mates.