Current DTC P3000 , Readiness DTC P0300 , P000A & P0125

welcome to priuschat! could be your hybrid battery. have you checked the fan for clogging?

 

Oh my. This one is over my head for sure. OBD codes show questionable traction battery and also misfires. One of the codes doesn't show up in the list I normally use for Prius. Also there is a question about coolant temp. for closed loop fuel control. (P0125)

You can refer to Complete list OBDII codes - GreenHybrid - Hybrid Cars for the list of codes I am looking at.

Hopefully Patrick Wong will chime in on this thread. It definitely appears you have more than one problem with your Prius. I think you will find in the end you will be looking at traction battery repair or replacement plus other items to get your Prius back up to speed.

If you can afford a diagnostic fee, you might consider having Toyota take a look at your Prius and then go from there.

P3000 HV Battery Malfunction
P0300 Random/Multiple Cylinder Misfire Detected
P000A - CODE NOT FOUND
P0125 Insufficient Coolant Temperature For Closed Loop Fuel Control

Oh, I almost forgot my manners! "Welcome to Prius Chat"!

 

Some questions: Has it ever been in an accident? What is your location? What type of reader did you use to get the codes? Sometimes generic readers give false readings, like the P000A.

Assuming the P3000 is real, and it seems to be likely, there are additional "freeze frame" data that need to be read to pin point the problem. One of the possibilities is "HV battery cooling system malfunction". It could be related to the Battery ECU. There are others possibilities, but just guesses at this point.

Does the battery State of Charge indicator go from purple bars to green bars and back rapidly? That is also an indication of HV battery failure.

The P0125 could be related to the temp sensor, or the wires going to it. What is happening when this DTC is logged is the coolant temp sensor is not changing resistance in response to coolant flow in the first couple of minutes of engine warm up. Do you feel warm coolant flowing in the hoses after the engine runs?

The P0300 could be caused by many things, like wiring faults, leaks in hoses, or a dirty MAF. It would be a good idea to clean the MAF if it has not been done.

I'm sure others will chime in soon. Good luck.

 

Is the fan for the battery still blowing all of the time? Do you see any warning lights on the dash? Is the battery level on the MFD going from top to bottom and back to the top quickly? (All green to all red)

 

As it is a 2005 with 210,000 miles, I suspect that your traction battery has reached the end of its life. It may need replacement, or you might be able to get some more life out of the battery with faulty module replacement and rebalancing. Where are you located? You can drive in this condition, but you will find the car to be sluggish and accelerate poorly. Note that when moving at a constant speed on flat terrain, the battery does not see any charging or discharging. Therefore you can drive under those conditions. It is starting and stopping, and going up and down hills, which require a good traction battery.

 

Woops...Sorry Ron, missed that. Late at night.

 

Replace the entire battery if you can afford it. If not, replace at least the three modules: the one at 7.2V and the two in the photo that are leaking electrolyte.

 

Here are some threads to look at (there are a couple of others to search out) to help decide if you want to replace and rebalance the modules:

Gen II Prius Individual Battery Module Replacement | PriusChat
Prius Battery rebalance thread | PriusChat
Another Gen II Rebalancing Thread | PriusChat

Now you can see why the battery fan was working so hard, with the heat being sufficient to melt plastic. I see that those are GenI cells, which are not as rugged as the GenII cells. It might indeed be better to replace the whole unit, unless your time is not going to enter into the equation.

 

If you replace the leaking cells and the weak one, make sure you take the time to balance the pack. And pay close attention to torque ratings. The cells are real easy to strip out and break the terminals.

If you can afford a different pack, you have options there also. You can check local scrap yards, as well as purchase remanufactured packs from various locations. If you will update your profile with your location, we might be able to point you to a particular vendor in your area that would have a replacement pack for you to save you time and maybe a few bucks too. In some parts of the USA there are companies that will come to you and replace the battery for you with either a rebuilt one or a new one. Of course each company will be different so if you do something other than DIY, take the time to investigate all of the courses that are available to you in your locale.

 

Hi there and welcome,

I have a question too.

When you undid the nuts holding the bus bars to the battery terminals, did you happen to notice if the nut on the stud that you have marked with a black dot (the most melted cell), was not tight? I'm wondering if this fault was caused by a loose connection causing resistive heating of that terminal, rather than the cells inside the module being worn out or failed.

If it was loose, the rest of your battery may still be worth repairing.

 

Time will tell if you will need to do more work. As the pack ages, you will probably need to continue to do the "whack a mole' process that you did. You are not the first to simply swap cells and not balance.

Keep us posted on your progress and best of luck to you!

 

Well, I hope you don't cone back with same issues.
Kinda like a wack a mule approach. No balancing, nothing?

 

Well, it's been over three and half years!