First Glitch (419 MI)

Hi Jeri... and welcome to the Prius world !!

I, from time to time, have experienced a similar effect. It seems to happen when I push the "start" button and quickly try to shift into reverse. Never happens when I wait a couple of seconds until I hear the "beep-beep" telling me that Ernestine* (my Prius) lets me know she is ready to go.

My fuel economy has been steadily improving with more miles on the odometer. I also plan to change to synthetic oil at the 10,000 mile service having heard that 5W-30 (as recommended) can improve fuel economy by as much as 10% - we shall see.

*Thanks to the sometimes strange, even innane responses I get from the NAV lady when I make a verbal request, I named my Prius "Ernestine" after Lili Tomlin's telephone operator character. Sometimes when I say "Go Home," Ernestine responds "Showing restaurant icons" or some other strange response. Even so, I do finally get an appropriate response and enjoy the NAV system. Rather than be irritated, I view her responses as entertainment and have a chuckle.

 

The hybrid ECU (the computer that controls the ICE and the electric motors) has a mind of its own. You can't "make" it turn the ICE off if it doesn't want to. Don't worry for now if the engine stays on, especially during short (<15 minute) trips. Just let it do its thing.

That said, some factors that tend to keep the ICE running are:

Cold weather
Heat or air conditioning on
Low traction battery
Cold engine (short trip or cold weather)
Transmission in "B" mode

 

No, not the A/C compressor on the THII model. AC compressor is electric running off the HV battery.

 

I've had the same problem. I decided to try and diagnose when the failure to shift into gear occured. This is what I've discovered. The colder it is the longer it takes the "READY" light to come on. If you are too quick on the draw after pushing the power button when you go to shift to reverse or any gear as a matter of fact the car just goes to neutral. Just give the "ECU" time to have whole system power up before shifting to any gear. As far as the ICE turning off forget about it, when the heat or the defrosters is on. Just let it do its own thing. You are getting at least 30% better mileage than any other car out.

 

True, the compressor can run on battery, but running with the air conditioning on makes the ICE run more frequently and, when cold, run longer. Maybe your THS II is different than mine, but this is certainly my experience.

 

The comment was, that A/C keeps the ICE running. It might run more often if your SOC is down to 2 bars, but it doesn't keep it running. Heat demand might, since it needs the ICE to create the heat. As others have noted, isn't it strange you need ICE to get heat?