P0A93 - Inverter Water Pump Failure

Hi All,

I have a 2008 Prius with 176000 miles on it. I have owned it since 117k miles. Several of you helped me around 161,000 when I had questions about replacing my battery pack as it died. I had that replaced at 161000 and the only other work I have had to do was around 165000 I had to replace the "standard" battery. Now let me bring you to this weekend. I am driving home from church yesterday on the highway at about 75 miles an hour and all the sudden my car throws the P0A93 code. The air stopped blowing cold, the car was a bit strange from the stand point the car wanted to go to high RPM's when over 60 miles an hour. I researched online, including this forum and everything pointed to replacing the inverter water pump. So I dropped the car off with Tires Plus since they were open today and they replaced it. They also found a small leak in my regular water pump and I told them go ahead and replace it too so it doesn't go out on me later causing any more inconvenience.

I go to pick it up at 2PM today, drive it off and within 7 miles it throws the P0A93. I turn around they take it right in and I tell them to check to make sure it's bled out and there are no air pockets and that the radiator fans are blowing. They have it about 45 minutes, make sure there is no air and hand it back saying maybe the battery is overheating causing the car to throw codes.

So I drive it home, mostly backroads under 60 miles an hour. The code stays on, even if erased it pops right back on. One thing I noticed is if I had the car at a steady speed, say around 58 miles an hour, I noticed a slight jump in the car. Very slight jump, jump, jump. Like as slight quick acceleration. If you were not driving and paying close attention you might mistake it for a bumpy road if you noticed anything at all. However if paying attention you could also here a slight jump in rpms at the same time.

The air stays cold the entire time. So I pull it on the highway the last mile or so, run it hard, up about 75 mph and car wants to run at high rpms. I get off the highway, my house is about 3 tenths of a mile from the highway and as I pull up to my house the last tenth of a mile, the brake light comes on and is beeping as if I am driving with the emergency brake on. No new code in scanner, just going berzerk.

I turn the car off and back on in my driveway the brake light is off this time. This all makes me think I am having a problem with hopefully my 12 volt. It could be the hybrid battery pack, but I did see another thread with a prius driver was getting this code but with cold air and said after replacing battery it went away and stayed away. Any additional thoughts?

My toyota dealership is about 1/4 of a mile from my office, so I think I will just drop it off with them in the morning, explain everything and see if they can't confirm it's the battery. Again, I have only had the batterly like 6 months and 10k miles, so I would expect this would be covered under warranty.

Thanks in advance for your feedback.

 

My only issue is I went back and had the mechanic check for air in the inverter system. I guess it's possible even though he went back and forth to his computer several times (checking instructions) and bled the car and confirmed for me there was no air in it, that there is still air. I also suppose since he replaced the main water pump at the same time there could be air in that one he missed too. If I take it to Toyota and it ends up being air in the system, I will be getting the cost of Toyota to fix it taken off my repair bill by tires plus. I will let you all know the end result to this as it's usually my biggest pet peeve with forums like this is the posters tend to submit an issue and seem to disappear after they presumably get it resolved without providing the final outcome.

If anyone else has thoughts please let me know. If you have experienced this and come to a resolution I'd love to know what it was.

 

I have not, I could try that. It's been a crazy weekend and just hadn't gotten around to that. I did just find something odd. The inverter pump is making a normal aquarium like small hum, smooth sounding. If I follow the line up to the coolant reservoir it vibrates all the way up the hose. The coolant resevior is filled to the full line and yet there is no visible movement of the fluid in the reservoir at all. So I am getting the impression that the coolant may indeed have an air bubble in there despite the mechanics efforts to bleed. I did see a video somewhere today that showed the coolant moving while car was in ACC mode and pump running. Mine is not moving at all, it's at a dead stop visibly, which I find odd and kind of pisses me off because the mechanic was just saying that the pump is turning on, the fluid is full and I have bled it there are no air bubbles. But everything I was reading tells me there should be visible movement of that fluid in the reservoir. Is there a picture of the bleed valve? I read it was right in front of the pump, but I can't seem to visibly locate the thing.

 

I found the bleed valve, need to find my voltage meter to check battery voltage, but check out this video. I show there is no movement in the reservoir but if you listen carefully when I hold the phone down over the pump there is a quiet but steady hum. I also open the bleed valve momentarily to show there is a steady trickle. So I am really confused, I guess a bubble trapped could have the pump running full time and vibrating the hose, but preventing any real movement in the fluid, resulting in what you see on this video?

 

Hi Patrick,

Tires Plus is a full service mechanic shop. I have had tons of repairs over the years with them. They told me they had to lookup changing the inverter pump and made it sound like that was a first. So in short this isn't a run of the mill tire shop but at the same time I think this was a first go round on the inverter pump. They definitely got the correct part. As far as last time the coolant was changed in the inverter, probably in 2013 when the prior owner had the inverter water pump changed under recall per Toyota owners service history.

Your explanation of the overheating straining the battery and brakes etc... makes a Lott of sense as to why things happened the way they did. My guess is maybe the system needs flushed and bled so I will leave this to Toyota tomorrow and will deal with tires plus after the diagnosis. I will post an update here when I have one.

 

Thanks for the advice. Turns out there probably was an air bubble or a clog that cleared on its own. I drove to work this morning expecting to drop it off to Toyota for examination, however it never through the code even driving 80mph with AC on and sitting in a drive through line ordering breakfast. I was a bit puzzled and when I got to work, turned the car off, turn it onto ACC mode and opened the resevoir and what do you know, very visible movement of the fluid. I suspect an air bubble moved on it's own overnight or when I opened the bleed valve for that video yesterday. The other possibility is that there was junk clogged and if that's the case of course that could reoccur. So I will be monitoring and let you guys know if the problem comes back up, but for the moment appears replacing the pump did do the trick.

 

OK all the light came back on and I opened back up the reservior top and didn't see movement. Took it over to Toyota today to get it diagnosed/flushed figuring it was an air bubble.... So the mechanic at tires plus left the Hose Clamp on the lower hose on the inverter system and I never noticed it looking from up top and he never noticed it during the recheck because they didn't lift the car up. What a pain... needless to say my costs accrued at Toyota were promptly refunded by Tires Plus when I returned the pliers Toyota took off the hose.

Per toyota the coolant is flushed and all is working well. Thanks for your input during this process.

 

Hi Franken,

Not sure if you have misunderstood some of my posts. The inverter water pump was replaced. I think it's pretty standard during replacement of that pump to clamp both the upper and lower hoses running to and from that pump. This is what the mechanic did at Tires Plus and other than forgetting to take the clamp off (which is a pretty big deal) he did the repair properly. Since I didn't realize the hose still had a clamp on it and I was still receiving a P0A93 code, I took the car to Toyota and that's where they determined the clamp was still on. So they removed the clamp and I had Toyota at that time perform a coolant flush on the inverter coolant system. I then went back to Tires Plus and received a refund for the labor costs at toyota regarding the diagnostic etc...

Hope this clears it up. Car has been running like a champ since.