Please help -- Engine Coolant Problem

Quote from other source The DTC code is P1121 which I decode as "Coolant Flow Control Valve Position Sensor Stuck".

I had some difficulty getting the air out of the engine coolant pathways when I changed my engine coolant. I thought I had sufficiently 'bleed' the coolant, but the engine temperature via my scanguage headed above 210 F on my way to work on a highway. I got off the expressway, checked the reservoir, still had coolant. I topped it off. Back on the freeway, I noticed the engine temp went down under acceleration, so I spent some time accelerating and slowing down , this eventually solved the problem for me. I would not generally encourage this without a temperature gauge for the coolant, which I checked with a scangauge.


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The standard way to bleed coolant is to use a vacuum device to help remove air; dealers use this.

P3000, HV battery malfunction.

Patrick gave some info here
http://priuschat.com/forums/gen-ii-prius-care-maintenance-troubleshooting/49355-code-p3000.html

I do not see the connection between the two, anyone else?

 

Start with purging air out of the engine coolant circuit;
then reset codes by disconnecting the 12V;
Any new codes will require troubleshooting.

Did you ask the dealer what work would be done for the $2000 ?

 

Here are my suggestions:

1) Did you open the bleed valve on top of the radiator, towards the driver's side, to help the air to come out? Need an Allen hex key to open it, I don't recall the size.

2) Did you squeeze the radiator hoses to encourage fluid to flow and air bubbles to rise out of the system?

3) While running the engine with the heater set to MAX HEAT, did you rev up the engine to heat it up, which would result in the thermostat opening so that fluid would flow freely within the coolant system? You need to do this for an extended period: 15-20 minutes, until the cabin heater produces good heat and you don't hear air bubbles in the system. <Don't worry about the fact that your mpg reading per the MFD is going to look bad.>

4) If you opened all three drains (engine block, radiator and coolant heat recovery canister) then you should use around 6 US quarts of coolant.

5) Since the coolant valve has three hoses leading to it, are you sure that you connected the correct hose to each valve fitting?

Regarding DTC P3000, did the car run out of fuel recently, or was the car left in N for an extended period? What was the first dealer planning to do that would cost $2K? That DTC is produced by the hybrid vehicle ECU because it has received a malfunction signal from the traction battery ECU. Usually the battery ECU will also produce a DTC that may help to decide exactly what the problem is.

After you restore proper engine coolant circulation, then make the car IG-OFF, disconnect the negative 12V battery terminal cable where it connects to the body for 5 min., then reconnect and see if you still have warning lights come up. If so then you'll probably have to have your car serviced by the dealer unless you can find out what the diagnosis was and determine whether you can take care of the issue yourself.

 

I don't have a photo.

Remove the black plastic radiator cover. Look at the sheet metal that runs over the top of the radiator. Find an access hole in the sheet metal, probably 1/4" diameter or so, towards the driver's side. That provides access to the radiator bleed valve.

The most comprehensive repair manual is available on techinfo.toyota.com and it does require a subscription. Minimum is $15 for a two-day access period. Or you can buy the Toyota paper repair manuals which will cost ~$500 if you buy the whole set.

Since P1121 is gone, that probably means that you installed the valve correctly.

When the overheating light comes on, the cylinder head temp is probably around 210 degrees F. Normal is 185-195 degrees F. Boiling point may be around 220-230 degrees F given the system pressurization, and if the engine reaches that point it will probably be damaged.

After the car cools off, see if the coolant level has dropped (check the radiator cap as well as the overflow container) and if so, add fluid to top off.

It's much better to be purging the air out of the system while the car is parked on the driveway because not much fuel is required to rev up the engine, thus it won't generate that much heat. When you are driving uphill, the engine is under substantial load so it will consume a relatively large amount of fuel which causes localized hot spots if the coolant flow is not normal.

 

I haven't realized that the margin of safety is so low. When I did full grill block in the winter the Scangague sometimes showed max coolant T of 204 F and there were two occasions when it showed 209 F. At the time I thought that's just a few degrees Celsius above the usual 191 or 193 F - no big deal I (foolishly) thought. At least there were no warning lights. Next winter I will be more careful.

 

Yes, if this was my car I would not be comfortable running the engine coolant temp so high.

 

Thanks! Another factor I forgot to mention is that those were recorded peak T - the observed running T was lower (by glancing at the ScanGauge from time to time) - there seems to be enough hysteresis in the system that the T would reach some peak value and then drop back down to some lower steady value - maybe when a valve open/close or fan on/off etc. At any rate you advice is well taken as always. Thanks!