2016 Slips into Neutral

This isn't going to help you directly, but huh, I'd never heard of DTCs starting with X before. P, C, B, and U are the only kind I know of. Is @Elektroingenieur still around? Are those some newfangled addition to OBD?

 

Thats an unusual one for sure. I think I read of something wierd when the hybrid battery gets too low and wont move forward in another thread a while back (several years ago, not exactly your issue but similar). How on earth it slipped into neutral is definitely a mystery.

 

I'm guessing the 2016 Model Two has the NiMH traction battery instead of Li-Ion and yours is at its end-of-life. BTW, how many miles on her?

One bar on the traction battery should not happen unless you are climbing a long hill and all the ICE power is needed for traction. When the car is still and idling, it should be recharging the traction battery, and likely why the car moved onto the tow vehicle under its own power after the wait.

The other thing you could check is the health of the 12V battery.

Perhaps another contributing factor would be traction battery cooling. Maybe your air vents under the rear seat are blocked, or the dust filter is blocked, or the cooling fan failed. This could lead to an overheated traction battery and the system decides not to charge it for safety. Sitting in the parking lot waiting for the tow would also cool the traction battery enough to be useful again.

 

FYI: Mine (2016 Prius three) sometimes goes to one bar during startup and driving on traction battery until the warm up cycle has completed. Has done that since brand new. I usually try and give her a decent charge before garaging mine for the night too, by keeping it from running on battery during the last part of my commute to avoid draining the battery during the warm up cycle.

 

Is the Three NiMH battery or Li-Ion? My 2016 Three Touring is Li-Ion, and experience zero traction battery issues since new (8 years) and 80K miles. No rapid / wild SOC swings, never 1 bar, etc. Yes, it will go full bars going downhill (because we have a lot of hills in Colorado), but never runs on low bars going up hills. Sometimes, when doing a lot of parking lot crawling in EV, it will drop low enough to force the ICE to kick in. Same thing when parked in READY mode, sometimes the battery will discharge enough to force the ICE to kick on.

A comment about your post: How do you drive on traction battery until the warm up cycle has completed? Once the ICE is running, whether warm-up cycle has completed or not, you are running on both ICE and traction. Same comment for keeping it from running on battery during the last part of your commute. How do you do that? The traction battery is always involved, whether in HV or EV modes. The Synergy Drive manages the SOC of the traction battery, you really don't have much say in the matter.

 

In my experience, whenever your down to one bar the ICE is on, recharging your traction battery. It shouldn't matter if the car is in park, drive or neutral, MEG1 should be sending power to your traction battery.
Have the dealer check your software revisions and make sure they're all up to date. There may be some glitchy software that they didn't bother to update. If you do have a NiMH battery pack, run the Dr Prius app on it to check the status of the pack or have the dealer do it. I wouldn't trust that dealership too much if you find out they missed a software patch, what other shotty work have they done?
Switch your base display to one of those that displays ICE regen. and battery draw. That way you know if the battery is getting it's regen charge. Simple display, red arrows - battery draw, green arrows battery recharge, or both when your off the gas pedal and coasting.

Hope this helps.....

PS. Don't forget to stop by an auto parts store for a free 12V battery test, like @FuelMiser stated. I personally don't think this would be an issue since the 12V DC-DC converter should be running and providing all the juice the cars' internal should need; but you never know. Also look for signs of rodents chewing on your wiring harness.

 

I agree about Park and Drive, but if you're in Neutral, the hybrid drive is disconnected and you will not be charging your traction battery.

 

I'll need to check that next time my ICE fires up.
On a normal car, when you put it into neutral, the transmission disconnects the input shaft from the output shaft - so the car can roll free. I don't believe the transmission input shaft (clutch) is disconnected from the motor. I'll report back in a few days.

 

No, the traction battery is required for any operation. The systems are completely connected.

If the traction battery fails, your car is bricked and I'm pretty sure you would get a christmas tree of warning lights if the hybrid system fails like that.

In your situation, the car recovered after a period of "cooling off" so I think the traction battery just overheated temporarily.

 

Which is something Hybrid Assistant would show clear as day as it displays the battery and air intake temperatures, amongst other temperatures like engine and inverter coolants and MG1/2 temperature.




Hybrid Assistant is always running when I go for a more than a few km drive.

 

The Prius transmission input shaft has no clutch. There is a torque damper on it, which is constructed sort of like a clutch, but missing any way to release it.

That makes the Prius transmission a lot like most old-fashioned automatics, which also have no clutch on the input shaft. They're usually made with one or more planetary gear sets combined with oil-actuated clutch packs, brake bands, or both.

The idea of a brake band is that it clamps down on one component of a planetary gear set when you want to drive, and by holding that component from moving, it forces the other two to transmit torque. Release the brake band and that third component of the planetary set just spins free, and no meaningful torque is passed between the other two.

Neutral on a Prius just electrically breaks the circuits to the two motor-generators in the transaxle. Neither one will contribute anything to moving the car or to charging the traction battery. The traction battery doesn't get charged in neutral.

That also has the effect of letting MG1 spin free, just like an old auto-transmission part with its brake band released. When there is nothing to resist MG1 spinning free, there is no way for meaningful torque from the engine to reach the transmission output. The transmission's in neutral.