2004 Prius engine runs when when screen says it's off

<div class='quotetop'>QUOTE(GaryK @ Mar 4 2007, 06:53 PM) [snapback]400102[/snapback]</div>

There is NO indication on the MFD showing whether the ICE is on or off. There's no "cure".

 

<div class='quotetop'>QUOTE(GaryK @ Mar 4 2007, 11:07 PM) [snapback]400114[/snapback]</div>

If your recall was updated software, their have been a few cases where Prius shut down on the freeway.

The fix was to program the ICE to run a bit longer or to run at times in the past it would have shut down.

I have not seen a posting on shut down on the freeway since the update to software.

Of course take mechanic for a test ride to confirm would be a good idea.

 

<div class='quotetop'>QUOTE(GaryK @ Mar 4 2007, 08:07 PM) [snapback]400114[/snapback]</div>

I've noticed that too with my non-recalled '07. I understand that the MFD is an energy monitor but if the ICE is not charging the battery or moving the car it's not going to show any arrows, which is ok.
However I think you have a point because IF the ICE is not charging or moving the car then WHY is it on? The smart computers in the car should turn it off.
An answer I can think of, and take this from a new onwer, is that the ICE is running to stay warm.
Hope it helps.

 

<div class='quotetop'>QUOTE(GaryK @ Mar 4 2007, 10:07 PM) [snapback]400114[/snapback]</div>

Is your battery fully charged when you observe this? I can induce the "engine running" condition on a daily basis by going over a big hill on my way to work. At the bottom of the hill there is a STOP sign and 99% of the time my battery will be full. At that point the computer forces the engine to turn over to drain excess battery power.

It's a "feature" not a bug :lol:

 

My 04 does the same thing . . . prior to & after ECU upgrades. I'm guessing it does it sometimes because the smog crap feels the ICE ought to be warmer, as it tends to be happening below 70 degrees (of course if the batterys aren't full charged, that does it too). How I cure it: When you roll up to a stop, just prior to stopping I throw it in 'N'. Then as soon as it stops I throw it in 'P'. ICE stops. Then I just throw it back into 'D'.

Well it's corny, but it works . . . or I just let the dang ICE thing do it's thing, if other folks are in the car . . . so they won't know how OCD I am. :lol:

 

Hi GaryK,

There are a few reasons the engine may be running, while there are no arrows on the screen. Usually it has to do with Heat. Either heat to defrost the windows (do you have your defroster on?). Heat to warm up the inside of the car (do you have your Climate control set to Auto?). This usually only happens in my 2006 for the first 10 minutes of driving, however. After that the engine and cabin are warmed up to accomadate the 66 degree cabin temp I have set here during the winter.

The other issue is catalytic converter heat. Catalytic converters need to be warm for the chemical reactions that convert hydrocarbons to water and carbon dioxide to occur in the small amount of time it takes the exhaust gases to flow through. So, the car will run the engine after an extended stop light, or down hill glide to heat the catalytic converters back up.

I do not know how valid this is, but I have tried putting the car in park while at a stop light. On occaision this will cause the car to go into battery charge mode. Othertimes it does nothing. And sometimes the car will go into battery charge mode without being switched into park. It seems to me if the engine is running, the extra load of charging would at least help it stay in an efficient load zone, while also supplying waste heat to the climate controls and catalytic converter.

 

My observation: in heavy traffic (I spend a lot of time in it), the system sometimes seems to 'give up' on stopping and starting the ICE. It seems to happen after it has stopped the ICE and then immediately needed to start again because traffic is moving again. After a few of these incidents, the computer seems to give up and just keeps the ICE running. It will only stop after I completely stop the car for a few seconds, or after a certain timeout (?). If the battery does not need a charge (or cannot handle it, being too hot/too cold), you see no arrows when the ICE is running in this situation.

This 'I give up' situation is not the only time the ICE runs without powering anything, as others have noted, it also runs more often in cold weather to heat up the catalytic converter and the shivering life forms in the cabin.

Another somewhat related observation: after a cold start, the system of course runs the ICE to warm it up, but it seems to prefer using the battery for propulsion the first couple of minutes. Trying not to put too much load on the ICE when it's cold perhaps?