Transaxle issue; would appreciate your thoughts

Hello all,

This is kind of a long story so bear with me!

I've had my 2007 Prius for 4 years with no significant issues. It was just about to hit 140k when the triangle came on. I took it to a mechanic to read the codes and got P0A08. It started up one more time and then wouldn't start the third time, but started with a jump. Had it towed to Greentech EV and Hybrid Battery and they tested the inverter and pump before finally deciding it must be the 12v battery, which they then replaced. Apparently it had been draining quickly while the car was off.

I did some short drives around town and all was fine, so a week later I departed on a 1,000 mile road trip from Portland, OR to Yucca Valley, CA. Unfortunately, that was not the end of the story...

Day one of driving (around 350 miles) was totally fine). Day two, we get maybe 100-150 miles down the road and the triangle comes on along with the tire pressure sensor and VSC. Pull off the highway to collect ourselves and then head to an Auto Zone for a code read. They get C1241 and C1310. I explain to the dude at the store that the battery was just replaced and his theory is a bad connection. We decide to keep going since I think at this point it was just the triangle and it seemed like whatever triggered the other warning lights had subsided.

At some point around now I also noticed a pretty audible whirring noise on the left side of the car. My co-pilot thought it was just the wheels hitting the road, but it def didn't sound normal to me.

Well, an hour or so later those lights come back on and the car powers down on the highway. We pull off and I call a tow truck. After an hour or so of being off, we turn on the car just to see what happens and (I think??) the triangle is on warning lights are off so we drive to the local Toyota service center, which is closed. Absent any great options we decide to take back road for the last 100 or so miles to our destination. The next day we go to the local service center but of course NOW the triangle is off, so all I can do is give them the history. They run a $300 diagnostic (fun!) and find P0A2B-250 and P0A37-260.

The tech explained that this points to a malfunction with the temperature sensor and showed me how he was monitoring all the heating components - which are all behaving normally - which in his view points to the sensor itself being bad. Explains entire transaxle would need to be replaced. Shows us how to disconnect and reset the battery in future, so we can get where we're going. He also checked the fluid (fine) and replaced, and the coolant and wiring and found no issues.

Since the lights are off we decide to proceed cautiously to our destination, trying to go no faster than 70 (CA highways are very fast). Triangle comes on again (to my recollection it was just the triangle this time) so we pull off the road and luckily there's a service center a few miles away. They do a free health check (thank you Selma Toyota!) and find P0A2B-250 only.

We get back on the road and maintain a speed of under 60, and stay at a midpoint between there and our final destination so as not to stress the car. From that point forward - staying under 60 - no more warning lights have come on. I would estimate 200-300 miles since then.

I am now in a driving environment where I have to get on a 60mph highway every day to go anywhere, which is like the worst possible time for this problem to happen, so I need to figure out a solution (fix? buy new car?) asap. Your sage advice would be most appreciated!

 

Thanks for your response! I'm unfortunately already in CA so I can't take you up on your Corvallis offer. Is there any chance this could NOT be the temperature sensor? I found this old thread where the car owner changed the transaxle twice and that code ended up being I think the ECU (I thought I bookmarked the thread but can't find it.) A little worried I'll spend a bunch of money to replace it and that won't end up being the problem.

Also, what's the deal with the sort of howling noise on the driver's side? How does that fit into this scenario?

 

Thanks Brian! Two shops have tested the pump (I've also observed it working) and don't think it's that, but is it possible it's intermittent? I did find a mechanic out here to replace the transaxle for the amazing price of $1,500 plus the part, so I'm ready to move forward on that as long as I feel confident that's the issue.

 

The Toyota service center did in-depth testing and didn't find anything beyond the temp sensor issue. Obviously I can't speak to the depth of their knowledge, but the dude did spend some time with it...

 

I found a shop in my area with good review who can do it as soon as I have the part for $1,500 labor! What should I be looking for online when shopping for a used one? Some say 0 miles, which I don't understand...

 

Would it shut down on the highway though? Cause that happened once. The guy at the Toyota dealership drained and measured the fluid and said the correct amount was in there…

 

So is it possible the wheel bearing could be causing the sensor malfunction code? It sounds like the wind howling through an empty house and gets louder the faster I go and is way more audible when I take my foot off the gas. Almost can't hear it at all when I'm pressing the gas. This is the exact code from the health check at the dealer:
P0A2B-250, TEMPERATURE SENSOR CIRCUIT MALFUNCTION.

Or is there a scenario in which both things are just happening at once??

Yes, the Toyota service center mechanic emptied and measured the transmission fluid (said it looked fine) and refilled. I've now been driving it for over 300 miles with no red triangle (yet!) but the sound is very stressful.

 

Update: I made an appointment at an independent mechanic for Wednesday to try and figure out the noise, and from there determine if I need a new transaxle in addition to whatever is causing the noise. Hopefully I will make it the 25 miles there!

 

Does anyone have a Carfax or similar account and wouldn't mind running a VIN for me? There's a used transaxle an hour away but they don't know the mileage. Just want to make sure it isn't something crazy.

 

In case anyone dealing with the same issue sees this thread, it was a failed bearing in the transaxle. No idea why that would have happened at 141k miles and with the proper amount of fluid, but here we are. Bought a JDM used transaxle and am hoping for the best. Not super confidence inspiring with this car.