Check Hybrid System - No sub codes

I have a 2011 Prius with 250K. Bought it used about 1 month ago. I put just over 1,000 miles on before having issues. I drove to costco, filled up the gas tank, parked it and went to shop. Came back out and within 10 minutes on the freeway I got the triangle of death, VSC, and (!) on the dash with "check hybrid system". Battery is charging just fine, held charge ok. AC compressor was recently replaced and the hybrid battery was replaced (not OE but from Greentec auto as refurbished) 2 months ago by previous owner.

When this alert popped up I took it back to them to trouble shoot and/or warranty the battery. They put a new battery in, cleared the code and sent me on my way. "Check hybrid system" came back on within a few minutes. I don't have tech stream but they did so I left it with them to pull the sub codes. They had the car for almost 2 weeks and could not get any sub codes to pop. Only P0AA6 526. They swapped inverters even with no luck. The car drives fine, at least it seems that way. I was getting around 50mpg during the 1,000 miles I drove it.

They tested MG1 and MG2 with a megger and all values were said within range. They swapped inverter and that didn't work. They tried 3 total batteries and that didn't work. The 12V battery is fine. Finally, they decided to unplug the AC compressor and I got a call today they drove over 50 miles with it and left it on for 30 minutes and no warning lights. So I went and picked it up and was driving home with AC compressor unplugged and all seemed well. Thought I won and would need to just swap compressors but then after about 20 miles on the highway the same warning lights and "check hybrid system" popped up.

Any idea what could cause this and why TechStream will not show a sub code to isolate the issue? Transmission fluid was flushed about 350 miles before this happened with WS ATF, replaced struts, shocks, lower control arms, balljoint, stabilizers, etc as the car had 250K on it. Honestly seems to drive fine still and I can't figure out where to go from here. I have searched the forums for something similar to this and can't find anything as everyone has a sub code to go off of.

 

I appreciate it. I’ve spent some time diving into this. I’m just struggling to get someone to pull the specific INF sub code (612,611,613, etc). Sounds like what you’re suggesting is to manually start testing for resistance?

I am going to attempt one more shop that’s familiar with hybrids (they service a lot do the ride share Prius’s where I live). I’m not mechanically illiterate but I’m not a full blown mechanic. Bring in electric systems I I’m venturing into uncharted territory.

I cleared the code last night and drove 30 miles to work today. The code came on after about 25 miles (usually it’s immediate) and this time it was just the triangle of death and no VSC or (!). Being the warning light came on after swapping hybrid battery, inverter, and disconnecting the AC compressor I am a little worried it’s MG1 or MG2. But maybe it’s just a simple short somewhere else in the system.

Anyways, I’m gonna drop it off today and hopefully get a confirmed source of the issue. Good news is salvaged items like transaxles and inverters aren’t too costly. Big question is where to draw the line on a gen3 that’s a little rough around the edges and is approaching 300k. Still getting 50mpg and it’s driving just fine otherwise. Cost of cars right now is insane so I’d rather invest a little and recoup in ROI down the line.

 

Yup. I have read that almost anything can cause this issue. Everyone I talk to keeps saying it's probably the Greentec Auto battery but I am unsure because they replaced it immediately when I brought it back, then again swapped it. So 3 separate batteries still caused it. They offer 48 month unlimited mileage warranties on them so I would think maybe they aren't all complete junk compared to OE.

But yeah, it has happened in cool weather, hot weather, on the highway, parked level, parked in the driveway, etc. Sometimes it lights up within 3 minutes on the car, sometimes it doesn't for 30 minutes. Now it's only only displaying the triangle and nothing else where before it had VSC, and (!). I have a feeling I am about to be very well versed in hybrid systems lol...

 

I definitely has cycled through multiple times. There was point there was quite a few miles put on after multiple start ups too. The car also never goes into limp mode. I just dropped it off at a shop who knows more than I would. Hopefully it's just something minor but with my luck it will end up being a transaxle issue lol.

I did check all of that on the compressor side and it looked ok. The car has also never left Arizona so there is little issue with corrosion. Overall, for how many miles are on it, it's pretty clean.

 

Still no sub codes to be thrown and no one can figure out why. I have had it with a reputable shop in the valley who specializes in toyota/lexus hybrids. They actually do lots of the prius fleet vehicles too. Lots of miles put on the car with no luck beyond P0AA6 526 - shop seems stumped. Next step is connector/terminals themselves. Everything else seems to test out ok. Inverter has been swapped, AC compressor swapped, multiple hybrid batteries (although refurbished - but what's the chance of 3 in a row being bad?). I know the refurbished batteries get a bad reputation so maybe it could be the issue but the cells have been tested.

At this point, I might just drive it into the ground until it stops driving. Drivability is not affected, the hybrid battery charges/discharges fine, the AC is ice cold... I just can't go into EV mode or use cruise control etc.

 

Sorry I have been MIA. Life took over. But I do have an update.

The culprit was the refurbished Greentec Auto battery (all 3 of them). I finally just bit the bullet and went OE. I’ve put over 2000 miles on it the last 2 weeks and it’s been perfect.

Buy once cry once I suppose. Both shops said they no longer mess with refurbished 3rd party batteries because this happens all too often. I know many people have good luck with them but I went through 3 in 3 weeks and all 3 seem to have been problematic.

 

I was not aware they are in short supply right now. It was ordered/received same day. I live in Arizona. Was not the cheapest of fixes but at least it's done and over with.

 

lol right? I bought the car used and the previous owner 2 months prior spent 1600 dollars on this 3rd party battery. I tried so hard to make their warranty work for me. Just not reliable at all and it gets to a point where time is worth more than money.

Do it right once and move on.