I bought 2010 with blown head gasket.
Hooked up my ODB II scanner and pulled the following codes
P0118 - Temperature sensor reading high (Duh)
P0300, P0301, P0303 - Misfire random, Cyl 1, Cyl 3 (Again Duh)
P261B - Water Pump Malfunction (The root cause of all problems)
P0A80 - Replace hybrid battery
P3022 - Block 12 of Hybrid battery bad
U0100 - ECM/PCM not communicating
I have owned Toyotas in the past and currently own 2 plus the Prius. This is my first experience with a Hybrid. I replaced the head gasket etc. and fixed/replaced all mechanical problems. I purchased a good used hybrid battery and replaced that as well. Car will start on Hybrid power and within 30 seconds the gas engine kicks in. I can drive car (literally) a few yards and "Check Hybrid System" comes on and car shuts off. I unplug the heavy white wire in fuse box under hood and orange connector at hybrid battery for a few minutes and then plug both back in. Car does same thing again. I thought maybe I need to clear the codes to correct the problem. I have a Innova 5110 code reader that I have used on my other Toyotas and my Dodge pickup. I push the "Erase" button and confirm, scanner says "Done" and does another read. Codes are still there. I have unplugged code reader, turned off car, plug in scanner, turn on car, codes still there. I borrowed a code reader with more functions and still no luck. Is there a trick or a special machine to clear codes on a Prius? And could this be why my car only runs for a minute and shuts off, it still thinks these problems are there? Ideas or suggestions?

 

This is not a "need to clear codes" situation. This is 99.999% certain a "need to fix car" situation.

"a good used hybrid battery" - this is rarely the case especially for Gen3 Prius. They HAMMER their packs. Unless it's an original pack pulled from a car with less than 60K miles, it's probably not good.

Just making sure - you replaced the water pump too? New long life Denso/NGK iridium plugs?

I have no idea what the heavy white wire is in the fuse box, but if it's the main feed from the 12V, then good. The only reason you should ever remove the safety plug from the hybrid battery is if you need protection from high voltage. Its removal does absolutely nothing else. It can't "reset" anything. The hybrid battery is completely isolated from the HV system when the car is off.

Disconnect the 12V battery for 2 minutes.
Reconnect
(the above clears ALL codes except permanent ones)
Start car and attempt to drive.
If additional codes are present, fix the problems.

Codes have 4 flags:

1. Current - active present code
2. Historical - detected, but met criteria for self-clear
3. Pending - detected, but hasn't fulfilled all critieria to set a current code.
4. Permanent - will not be cleared via 12V disconnect or clearing codes. P0A80 is one of these. This remains present to prevent some a$$hole from clearing the codes and trying to sell the car. The car will only clear the code after the conditions are not detected for X consecutive drive cycles.

When using Toyota Techstream, one can clearly see which they fall into. Cheap code readers may report them; however, they often don't identify the flag - you'll just see another copy of the same code.

When a permanent code is cleared, it ONLY shows up as "permanent" - not current, historical or pending, and it in no way impacts the car. it's just a "permanent" record of the code.

Again, you have codes because 1) you need to fix your car, or 2) your 12V is bad - which is just a specific condition for #1 (you'd almost certainly get a lot more codes if your 12V was bad)

 

Thank you for your response. That is the most intelligent answer I have received on 4 different forums. If you need a laugh, let me know, I'll forward a few of them to you. Yes to water pump and plugs. I will double check my code reader to see if it indicates permanent or whatever. The hybrid battery is reading 6 bars.
Thanks again.

 

Unfortunately, sh!te batteries may show six bars, AND that's the default after a reset.

Let me know what your current codes are when you get a chance.

There's also a sensor associated with the water pump. Leaving it disconnected, or it failing will continue to give the P261B code.

 

OK, so.....
I hooked up my code reader and get all the codes mentioned above. P0118 is in there 2 times, once as pending and once as permanent. ALL of the other codes are 'Permanent'.

 

Listed causes:

• Open in engine coolant temperature sensor circuit
• Engine coolant temperature sensor
• ECM

If you can check the coolant temperature via OBD,

Open circuit will show -40°F or °C
Short circuit will show 140°C or 284°F or higher

P0118 will trigger "check hybrid system"