P1121 - Coolant Control Valve Replacement (with pics)

Hello Durunron,

Thank you for your advice on maitenace mode and the link. One thing I did not do is to unplug the Coolant heat storage water pump connector, should I disconnect this connector while running maintenace mode then refill?

Thanks again,

 

That is not necessary. Rev up the engine 10-15 minutes at a time, to help promote fluid circulation. The engine needs to warm up so that the thermostat opens and you can feel the hose from the thermostat housing get warm. Squeeze the hose to help get air bubbles out.

The radiator has a bleed valve which is accessible via a hole in the sheet metal frame on top of the radiator. I have also found that the Lisle funnel is very helpful in getting air out of the system.

Pls see my posts #22 and 42 in the referenced string:
Changing engine coolant | Page 3 | PriusChat

and the following string:
How to replace engine coolant pump and thermostat | PriusChat

 

I can not truthfully answer that question. Patrick Wong posted a paper clip trick somewhere here on PC to run that pump if you are doing a full change, but I don't think you will have to worry about that.

Just keep adding the coolant with each warm up - cool down cycle. Make sure you fill both the overflow bottle and the radiator every time when it cools down. Once you start getting heat inside, you should be close to getting most of the air out. Remember it takes a few tries. Just be patient and don't overheat the engine. The idea is to get the thermostat open, thus allowing the coolant to circulate, then add more coolant as needed until it is full again.

Thank you Patrick for weighing in here. You know a lot more about this than me...

 

Hello Patrick,

Thank you very much. I will read and try tomorrow.

Today I have time to work on the car, with the instruction to jump the CHS and turn OFF then ON the Climate control (Fan on/off of the climate display). My heater is start working, I was able to add cooling fluid in to the Radiator.

Thank you for your help.

 

This discussion was very helpful. I ordered the new part and did all the steps listed here and ended up collecting about a gallon and a half of fluid. When I finished installing the part and began the process of adding the new fluid I only was able to get 2/3 of a gallon of fluid back into the tank before it began to overflow. I tried driving it around for a bit and the fluid level went down just a hair and I topped it off again. I then took it for a half and hour drive to test it which included driving on the highway for about 5 mins. While I was driving the check engine light came back on and later in my ride (specifically when I was accelerating onto the highway) the "Problem" beep and red triangle appeared and the icon on the digital display indicating coolant temperature warning, suggesting the coolant was too hot. I stopped checked the coolant level and it still was at the full line. I let the engine cool and took it for another drive, same thing happened again. I can't figure out what is wrong, but its almost as if the fluid is getting circulated around the system correctly and suggestions? Thx

 

What is wrong is that you obviously still have air in the engine coolant loop since you drained six quarts yet only added less than 3 quarts.

More than 3 quarts of fluid remain to be added. Check the fluid level in the radiator itself, not just the overflow tank. Please recognize that air can be easily trapped by the cabin heater core as well as the coolant heat recovery system.

My post #42 above contains two links which discuss how to get air out of the engine coolant loop. Please read the first link in particular.

Do not drive the car until you have managed to add substantially more coolant to the engine coolant loop unless you want to risk damage to the engine. Such damage can be easily incurred since the engine head and block both are of aluminum construction.

 

Has anyone else in California got this done under warranty? My car threw off a P1121 earlier today and the coolant levels in both the overflow tanks looks good, so a coolant control valve replacement is in my future. I called the dealer right before they closed and they estimated $550 as the cost.

I have 146K miles on my 2007, so this could be a godsend!

Thanks.

 

unmesh59,

Don't forget the P1121 code can be set if the coolant is low in the radiator. With the Prius, looking at the overflow bottle at times will NOT reveal a low coolant level in the radiator. There have been instances whereas the overflow bottle would be full, but the radiator be low. It is best to check the level visually by removing the cap from the radiator. Fluid should be to the top of the neck. The picture below will illustrate what the radiator should look like when it is full with the cap removed.

Best of luck to you!

Ron (dorunron)

 

dorunron,

It took me a few minutes to figure out what you were showing but I was eventually able to confirm that the coolant does come to the top of the radiator.

Thanks.

 

Glad it helped you!

 

FWIW, the Check Light went away and I'm waiting to see if it reappears before taking further action.

 

Have mine apart right now, but can't figure out how to disconnect the electric connection. Have all the hoses and mounting bolts out, but how do I disconnect the electric. part # 16670-21010 , 2005 prius 220,000 miles. Only second repair of any kind needed. Thanks for any help.

 

Figured it out. new one is in and codes are gone. Thanks for the excellent write-up.

 

I think it would take less than 30 minutes to refill cooland by remove radiator cap. You need the run engine in the inspeciotn mode (see procedure on the top of page 3), then to go to MDF push Climate, then turn on the heater to high then turn off the heater by push OFF then back to on make sure Fan is on (you should feel the hot air in few minutes). I was having problem, only cool air blowing and the water level won't go down, but by turn heater OFF in Climate then Fan on, water level started going down......

 

Sorry for the typos..

 

I have this issue and just saw that this procedure involves loosing a lot of coolant. And just yesterday, I drained and filled the coolant in the radiator with SLLC.

I searched around found this hose clamp. Think I'll get two three.
Radiator Hose Pinch-Off Pliers

Next is to order the part and find a good day with free hours to work on this.

 

I think there are 3 hoses on this procedure. Should we use three Radiator Hose Pinch-Off Pliers instead of two?

 

I usually use 3.

 

Just got a P1121 code today. I wish I could change my own water coolant valve, but I don't have a lot of tools or faith in my abilities as to knowing what is what.... I am probably going to have to pay the dealership to fix it for me. It seems a lot of people are having this issue.

 

I changed out the Coolant Control Valve this past weekend. Took my time and completed the job in a few hours. I ended up not buying the pinch off pliers. Instead, I used stuff lying around that fits inside the hoses. (Kudos to anyone guessing correctly what I used to plug those hoses)

With this plug method, the coolant lost was minimal; at most 12 oz was lost. As for bleeding the air out, I just open the bleeder valve on the top of the radiator while adding the coolant to the radiator and the reservoir. Drove the Prius 60 miles that day with AC on. Everything seems normal.

Here is a pic of my old and new valve.