Mom's 2007 Prius on road trip, can't go over 45mph

I suggest that your mother should check the tire pressure on all four tires. Perhaps one tire is low and is rotating at a faster rate compared to the others, which is causing a problem with the skid control ECU.

If the inverter coolant pump has failed, typically the car will refuse to run when the inverter overheats, vs. being able to proceed at a slower speed. I have posted on how to replace the inverter coolant pump here:
How to Replace the Inverter Coolant Pump | PriusChat

It is possible that the transaxle has failed. Has a warning icon appeared in the upper left corner of the MFD?

 

How many miles on the car?

 

Has anyone checked fluid levels? High tech car doesn't mean low tech things should be neglected.

 

Road trip sounds like a long trip. A triangle warning is serious. Random shift from 50 to neutral is dangerous on the highway! Get off the freeway and take it to a good Prius repair shop or dealer. Don't wait till she gets home if it's more than an hour away. 1st question: how old is the 12v battery?

 

Inverter Pump has failed.

P0A93 is the Inverter overheating. Not good. That same coolant loop that services the Inverter also is the coolant for the transmission so the car was driven with no trans coolant also. Odd that it didn't shut down the car.

Replace the Inverter pump and flush the Inverter coolant. I would replace the Invert coolant hoses also. I would also replace the trans fluid as its probably toast too.

 

DTC P2238 points to a fault with the air/fuel ratio sensor.

 

An overheated inverter can cause the DC-DC converter to shut down, which then runs the 12V system very low. I think we've seen cases here where this has lead to other spurious errors. So I'd try just replacing the coolant pump at this stage. Also charge (or test) the 12V battery and clear the codes.

 

Unless you have the proper tools to diagnose the problem, you would need to get the codes read somewhere......the dealer will be more expensive but they surely can get to the bottom of things.

 

Get MiniVCI w/ Techstream (Amazon @ $27 or eBay). This will give you the same dealer level diagnosis capability; no more paying $100+ per incidence. With this tool, you'll no longer ask what "this" code means, but now ask "How do I ..."

All those Bluetooth OBDII readers are a waste of time and money for the Prius, as those miss so many codes.

READ the following link in its entirety, and you will know what hardware is required, and how to set-up Techstream. There is even a link for 64 bit-OS set-cup. Again, READ the thread from the Tundra folks in its entirety, and you should not have any further questions.
TundraTalk.net - Toyota Tundra Discussion Forum - View Single Post - Offical TechStream software thread( settings and such)

If your mom is physically able to, she needs to check the tire pressure herself. A lot could have happened between the time the dealer supposedly checked the tire pressure, to present date. If she doesn't know how to do this, you need to teach her. Tire pressure fluctuates w/ temperature as you may know. Also, the dealers will only inflate the tires to the manufactured recommendation of 35/33. Many here believe this is too low, and many seem to go 40/38, or 42/40.

Art's Automotive provides a nice picture of Toyota 35/33, w/ lots of wear on the outer edges of the tires. Prius 30k Service

 

Make the Prius READY. Check the inverter coolant reservoir for fluid turbulence. If you do not see this then the inverter coolant pump failed.

 

I thought we determined that the inverter coolant pump failed back in May 2014?? Was it never replaced then when the op stated that the inverter coolant reservoir had no turbulence? In confused.

 

It may be the mom never took the car in for the Limited Service Campaign (LSC), or her VIN was not covered by the LSC. The LSC was specific on the model years covered and the VIN range. Unfortunately, this LSC is over so someone will have to pay to replace the inverter pump.

 

Whether or not the pump was replaced in 5/2014, the pump may have failed (again), or there may have been an installation error if the pump was replaced.

 

This is an old thread, but fits my symptoms nearly exactly - we've solved it, so I thought I'd post for future users.

While driving I had noticed the engine seemed to really run fast- it was trying to charge the traction battery (which was low because of a lot of sitting still with the AC running, but it was unusual that the car really seemed to struggle to accelerate from stoplights - noticeably strained compared to same condition without the pending failure (which hadn't fully occurred yet). A while later, the AC air speed suddenly dropped noticeably - strange, so I checked, but it was still set to "high" where we had left it. A couple miles later, we heard a long tone along with the "red triangle of death" followed by a couple other dash lights, then another tone a moment later with many more warning lights showing - check engine, VSC, ABS, tire pressure warning. Ironically, we had just filled up the gas tank also, 14 miles before this, but I want to point out, that is just a coincidence and is not part of the cause.

We were able to keep driving the last 1.5 mile home, no problem, and I immediately checked with my Torque app. P0A93 and P2238.


And I checked my custom view of battery and temperature readings and noted the traction battery was hotter than normal and the inverter was very hot, > 180 F.


After it all cooled down, I checked again and most dash lights were dark and it only showed the P0A93 code. This matched what I figured - the other lights and code were a cascade-of-failure effect... bogus. The real problem was the P0A93.



With the car on and "ready," I checked the inverter coolant reservoir... looked like a tranquil lake; no movement at all - silent.

Definitely a failed inverter coolant pump, or electrical problem for the pump. We figured the pump was bad.

We bought a new inverter coolant pump and replaced it; took about an hour because we were "learning," but could be done in 20 to 30 min using the technique we devised along the way - I note it below. After replacement, we cleared the code and checked the coolant reservoir - it was obviously turbulent. Sorry for bad pictures... they were captured from a video.


And when running on a warm day with the AC blasting, both stand-still and freeway speeds, the inverter heated up and cooled right back down as we expect it to, getting to a maximum of 136 F for just a moment and normally staying in the 110s.



REPLACEMENT TECHNIQUE:

We found what worked best for us was removing the front two bolts attaching the inverter to the frame and also the two bolts on the right side of the inverter mounting bracket (right above the inverter cooling pump) to completely remove the bracket. That left us very clear access to the pump (vertically), and with two of us working on it, one of us was able to hold the inverter up and to the left to make just enough room for the two fluid hoses to squeeze by (carefully) - the inverter's back mounting bolts were still in place. This allows the pump and hoses to be brought up above and in front of the inverter (between the radiator and inverter) for further pinching (to save fluid), unclamping, pump removal and replacement, then reinstallation. Definitely need two people for this process I described, but the whole thing could take only about 30 minutes.

 

Best way is pull the top of the front bumper down by removing about 6 crews then its easy to take out the headlight by removing three screws once headlight is out the inverter is right there easy to unbolt. I've done it a few times takes taking the light asy out. Takes about 5-10 minutes. Easy.

Thats how the dealer does it thats how Luscious does it.

With headlight out good time to change the bulb its going to fail sooner or later.