Hi everyone, I drive a 2013 Prius II with 188k miles. Two weeks ago while driving for a few hours I got the "Check hybrid system" message. I pulled over and the car wouldn't go into drive or reverse. I restarted it and I was able to drive home. I attached OBD2 and got the code P261B which I've read is the waterpump, but I also ran some test with the Dr.Prius app and got a different code P0A0F and some more errors "Poor Balance Block #9" "Weak Block Detected:7". I can't really pinpoint what P0A0F could be. I've driven the car for a few since and it seems fine. The check engine and check hybrid message went away. I watch the coolant temp and it's been normal. How should I proceed other than changing the waterpump? Thank you in advance Errors: P261B P0A0F Poor Balance Block #9 Weak Block Detected: 7
P261B is one of the trouble codes for a water pump problem. The engine control module has a special rule for whenever it is showing a water pump trouble code. If the engine coolant temperature ever reaches 105 ℃ (221 ℉) while any water pump trouble code is showing, the module shuts the engine right down. The power management control ECU (which is kind of the orchestra conductor for the car) wasn't expecting the engine to shut down, so it then gives the code P0A0F, which means "hey, the engine isn't running when I want it to!". Dr. Prius is also showing you some codes about possible upcoming battery issues, but none of that is as urgent as dealing with your water pump.
Thanks for responding. That's good to know that one code led to the other one. Is there a reason why the second code only shows in the Dr.Prius app and not the Torque app and vice versa? Is there anything else I should be changing while changing waterpump? I'm considering doing the thermostat since it's in the same area. Thanks
The thermostat is opposite the coolant pump. Kinda tricky to replace. If it is the original one, you'd likely be okay with leaving it in place. When you fill the coolant system, go very slowly. Doing it slowly and about 1-2 cups at a time, will allow the coolant to settle to the lowest points and push the air out. Fill to the B mark. Start the car and let the engine run until it shuts off on it's own. Check the coolant level and add coolant until it is just about the FULL line, at the seam. Then drive the around your local streets and try to keep the engine running as much as possible. When you get back home, check the coolant level. Add some if you need too. Then you won't have to waste time and fuel letting the engine run in maintainence for hours.....
The codes come from different ECUs: P261B is a code from the engine control module, and P0A0F is a code from the power management control ECU. There are only a few scan tools/apps being sold that can talk to all of the roughly two dozen ECUs in the car. Many will only show you codes from certain ECUs, giving you an incomplete picture.
