So last week I was driving on the freeway which I rarely do as I keep my Prius trips short and after about 30 minutes of 60mph driving I experienced the red triangle as well as almost running out of gas (blinking gas light). Thankfully, I turned around and made it home. I took it straight to an auto parts store and the only code that came up was P0A93 (which suggest inverter issue/pump). That was the only code that came up. Managed to replace the inverter pump with an OEM one after disconnecting the battery. Turned the car back on and the P0A93 code is gone along no red triangle. However now I'm hesitant to drive it. Are there any issues or codes that may pop up due to the inverter pump? Meaning is there something causing it to go bad that I will likely cause if I drive long-distance again? Thanks!
A high percentage of the time a P0A93 is due to temperatures rising in the inverter because the pump has failed (or is running but pumping insufficient volume of coolant). The lower percentage is the cooling fans not running. Which of these two is the cause of the code is indicated by the INF code set which you can read in the freeze-frame data. You need a competent OBD-II reader to access freeze-frame data. Having said that you will not be stuck if the P0A93 should come back. Just stop the car for half an hour to let the inverter cool down then continue the trip via surface roads at 45 MPH or less. Personally, if the pump was not running when you changed it and now it is running, I wouldn't worry and call it fixed unless something happens to say otherwise.
I'm also not certain that ECU really knows whether the pump is working or the fans are working or really why the temperature is high. I think it has several temperature sensors through the inverter and transmission and it may be programmed to make inferences about whether the coolant is flowing or not from the temperatures it sees in different places. So it might be possible for there also to be coin-lands-on-edge cases where there's a P0A93 because the temperature is high, and there'll be an INF code suggesting the pump or the fans as the usual suspect, but it turns out to be something weirder, like a clog. But for the most part, I'd go with the usual suspects.
I'm sure the repair manual has steps to cover clogging, so you can't go to wrong just following the RM steps for P0A93.
That code sets when the inverter temperature gets too high. For many people, they won't see this code even if they do have some deficiency because their driving pattern doesn't stress the cooling system. Only when they go on "extended" highway driving, or use A/C on a hot day for awhile, then things get hot. You might have had a bad pump (very common), or it could be a coolant flow restriction, or airflow restriction through the bottom of the radiator (dirt, leaf debris, etc). When possible, I like to confirm the fault (find my "smoking gun") before replacing parts. If you got all the air out of the system (via the bleeder valve by the inverter), and coolant flows through the reservoir, then all you can do is drive the car and see what happens. Ideally, get a "compatible" scantool so that you can monitor inverter temperature and see if that's steady. Posted via the PriusChat mobile app.
Thank you for the very comprehensive post. I appreciate all the replies above as well. Although the P0A93 code didn't reappear after checking the code with the auto-shop scanner, now I have a C1378 (capacitor communication circuit). Another thread mentioned that C1378 was fixed by securely re-attaching the 3 wires that go next to the brake box next to the 12v battery so i've tried that but haven't rechecked my OBD codes. Drove for a half an hour on the freeway and no codes/red triangle....so far. Very nervous driving when you know that something might go awry. Gonna take it out a few more times carefully but really would like to have it checked by a professional before any long trip.
Same problem with red triangle here 2years later. 07 Prius with 170k mi.. We were shooting down I-80 (mostly a downhill & cool.) and stopped with red triangle and got a 60 mile AAA+ tow home. I just happen to have a replacement electric inverter coolant in my back pocket, lol. Long story as I missed the recall by 2 years so I bought the part figuring it would go bad. How hard is it to r/r by owner ? I’ve done some heavy maintenance ( including HV battery replacement). Can’t see if fan 2 is spinning. Does the inverter pump share radiator water. So do you look at the plastic water overflow tank cool to see if water is moving ? My code reader would not find P0A93 code. OBD Fusion found and cleared both it and the red triangle fine. Been driving around town and it won’t return. Does this pump sit under the inverter ? Inverter was replaced by local Prius shop with a salvage yard one 2 years ago.
possible that the salvage inverter pump has gone bad too or is clogged up. its a really easy job. just take out the drivers' side headlight in total and you will have EZ access to the pump. Use clamps or pliers to keep the hoses from leaking while you replace it with a new inverter pump.
