Lots of lights, sometimes P0a93

09 Prius with 307k miles.

August 2021 - replaced inverter pump with Autozone part (P0a93 code)

April 2023 - replaced again with a new Autozone part (same P0a93 fault code)

May 2023 - replaced coolant control valve with OReillys part. P1121 code.

Fall 2023 - replaced coolant control valve for second time (Toyota part this time) P1121 code

Winter 2023, started using oil and I didn't know it. Ran very low before red triangle came on and I added oil (likely at 4-5000 miles since change). Tech set maintenance reqd to 5k but I usually only go 3k.

Winter 2023, new front brakes and rotors and axle.

All seemed well. Drove maybe 5000 miles since any issues (oil changes at 3k).

Two days ago it was very warm in MN. 50 degrees. Drove over 100 miles doing life and suddenly on highway:

Red triangle
Yellow exclamation mark
VSC light
ABS light
and yes CEL, but that's always on due to P0420 for my cat.

codes were P0420 (expected) and P0a93 (again!)

When i've had the inverter pump problem before, I clear codes, let things cool down, and try to drive home. I was forty miles away at this time.

I cleared the codes and sat for close to an hour. I checked the oil and it was just below the low mark with about five hundred miles till oil change was due. I drove one mile to a convenience store and added two quarts of oil.

Eventually I drove home with no further red triangle And no return of the p0a93. But all the other lights keep coming on.

(!)
VSC
ABS
and CEL

So...? Did my autozone inverter pump fail again for the second time?

Do I have something else going on? That's not throwing a code that I can read?

Why didn't the inverter pump code come back when the lights came back on?

Shall I change out the inverter pump yet again?

 

Well I am not sure what threw the p0a93 that I saw (and took screenshot) this week, but you are right... there is more.

Autozone reader shows

U0123 Lost communication with yaw rate sensor module

U0124 Lost communication with lateral acceleration sensor module

U0126 Lost communication with steering angle sensor module


So, I will search pc archives for those. Can I still drive?

I will check for the Inverter pump motion this afternoon. Good idea... But might it be possible for it to work intermittently? What else would cause P0a93?

 

Would it matter that the night everything lit up, I had 700lbs of people in the car and 250lbs of mulch? plus maybe 25lb dog, couple gallons of washer fluid, and miscellaneous backpacks, a suitcase, and winter coats and boots?

Maybe the heaviest load or close to it...

Made it home from autozone 14 miles with no lights this time. I did NOT pick up the part, on your advice.

 

Wow! Well as a UNC Tar Heel myself, I commend your spirit of adventure!! I've hauled a full size refrigerator to the hazardous waste drop-off myself, but that was only 6 miles at low speeds.

The load I had this week didn't feel heavy, just bulky and the dog had nowhere to go.

The dash lit up shortly after accelerating onto the highway. Might have reached cruising speed of 65mph or so.

Those U-codes still don't show on my reader so I guess I need to upgrade that. No idea when they appeared, but still doesn't explain the P0a93, and that doesn't explain the lights staying on when it didn't throw that code again.

Gonna sleep on it, upgrade my reader, and keep gathering clues.

I ran a 10 mile errand this evening with no dash lights coming on. Aaaargh!

 

I have learned my lesson about parts for sure! I should find a decent place to buy Toyota parts in my area.

Thank you for the ideas.

 

Well my new reader isn't here yet. Today I drove 60 miles round trip highway and 6 miles round trip suburb.

NO dash lights (except cat-related CEL) and no new codes on my old reader which doesn't read ABS codes.

No sign of the P0a93 again. Almost 50 degrees here.

So, I'm gonna get the new reader maybe tomorrow in the mail and see what I can see.

It might be too much to hope that it all was just a horrible mistake.

 

OK - here's the update.

1) after clearing the P0A93 code the night it happened, that has not recurred. I had never gotten the red triangle since any previous problem, so I believe this was triggered that night.
2) I got the new reader that reads ABS codes and I could read the same three codes that Autozone was able to read. Since my reader would have never shown those to me, I have no idea when they were thrown. So I cleared them (I assume my old code reader would never have seen them OR cleared them).
3) I've now driven over 500 miles and NO P0A93 and NO more ABS codes and no more crazy dash lights.

So - what the heck??? Do I need to be nervous to drive long road trips now? Could it have been the overload and accelerate to highway speed? Could the brake ABS codes have been thrown during service visit when I got new brakes, a wheel bearing, and an axle recently and just wasn't re-set?

I won't look a gift horse in the mouth, but I hate an unexplained problem that might recur unexpectedly in the middle of nowhere some day...

 

I got the Innova 5110. I still am not sure how to maximize the use of it, but can do the basics. I don't think it's capable of reading the inverter temperature. But I did add the ABS capabilities to my repertoire - I hadn't even known they existed before this issue.

THANK YOU for reminding me to check the pump. We've been setting daily high temp records this week, but it's still not up to 60 degrees so probably not impacting the need for the pump. Will it still run in relatively cool weather? It's raining and windy now, but I will add it to my list and get it done shortly.

 

Well, that's what I get for dawdling... Today, after about 60 miles of errands, and about 30 minutes of idling while waiting for a child to finish work, the lights came screaming on again:

Red triangle
(!)
VSC
ABS
CEL (always on due to cat)

This happened while NOT overloaded, but again just after coming up to speed on a hwy (70mph).

I pulled over and checked codes:

P0a93
P0420 (expected, but Innova says it's a serious error)
C1310 (abs code, new, I've never seen this before but never monitored abs codes at all anyway)

I drove about 2 miles, noticed I could NOT engage cruise control. Decided to make SURE I had oil. Pulled over again and turned car off and checked oil. It was tolerable (changed about 1500 miles ago).

I turned car on again and all lights went away except the red triangle (and CEL).

I drove about 7 miles home, cruise control now worked. Stayed 30-50mph.

Sat in driveway at idle and finally remembered to check for "turbulence" in coolant. NONE. Had been checking coolant levels and it's right between high and low. But there is NO movement when I look down in there with car in READY mode.

It wasn't even 40 degrees here today, but it was super sunny. Still, you wouldn't think the inverter would overheat in Minnesota in February. Yet - the code says that and the coolant is not circulating...

Is that coolant tank ONLY for the inverter coolant? (unrelated coolant control valve changed before Xmas)

Do I get rid of the SECOND autozone inverter pump and pony up for a Toyota one?

Only other thing I can think of to do is see if I can find someone with a better code reader/scanner and see if there might be something else going on.

AAAARGH.