P1121 - Coolant Control Valve Replacement (with pics)

Damn it! I wish I saw your post before working on my car - could've saved even more $ & a bunch of time that I spent searching for the right drain plugs at Lowe's (even with the help of absolutely useless store employees ) + I had a bunch of wine corks at home

 

Hi all! Need advice regarding bleeding.

Saw code P1122 a few months ago in CA in the summer heat. Checked the radiator fill neck - it was up to the cap level on a warmed up car. The car was shipped to PA on a truck early next morning. Using the forum (thanks everyone for their valuable inputs), made sure the code wasn't something that needs to be addressed urgently.

Just now got to dealing with this issue in need of passing inspection & registering car in PA. Checked the coolant level in radiator fill neck in the morning after a cold night - level was low. Couldn't determine coolant level in overflow during day or night using all possible flashlights & wiping the overflow tank - it's just not at all transparent in a 14-y/o car (same goes for reservoir but that one you can at least see from atop). Decided to minimize labor time & mess from spills - didn't drain systems. But for some reason I decided to top off the coolant in radiator fill neck, overflow tank, & reservoir before changing inner parts. Used a Spill Free Funnel Kit for radiator fill neck but still ended up spilling everything left in it when detaching it & overfilling the tank & reservoir .

Changed the 3-way coolant control valve & the inverter pump (following advice that it's time & just might as well while you're in there) using drain plugs for the hoses (still managed to spill some coolant from the 3-way valve) & refilling the new parts with as much new coolant as could fit into them before reattaching hoses.

When dealing with inverter coolant loop bleed valve, attached vinyl tube for venting back into the inverter reservoir. First used the paper clip method on the relay box like 5 times but just heard the pump work with a neat sound without noticeable changes. Then put car into IG-on & saw the coolant constantly flow back into the reservoir - no bubbles for another 5 minutes. Then put car to inspection mode with Max Heat & Max Fan Speed for 20 minutes - heat started going into cabin & kept getting warmer over time - I also started revving the engine after 20 mins & looked at all the data in the apps reading from OBD scanner (fault code not showing anymore btw). Sat like that for an hour occasionally checking the inverter coolant loop bleeding & the radiator fill neck with the no spill funnel occasionally letting out a bit of bubbles, mostly when I would squeeze the large diameter radiator hose on the driver's side, & going back to revving. It was 34 F/1 C outside, thus I wasn't sure how much time the whole system needs to properly warm up - got the coolant temp up to 170 F/77 C & the heat coming from vents in the cabin was actually HOT to touch. The large diameter radiator hose was warm (didn't seem hot) to touch. Couldn't hear any gurgling in the cabin, pump worked a bit to fill canister after turning off car.

However, when trying to get air out of the engine coolant system, I couldn't manage to open the valve via the hole on the stamped steel frame over the radiator using an Allen wrench - the plastic (or rubber?) thread is stripped. Do I have to disassemble the whole steel frame under the hood that's holding the inverter & everything else just to access the radiator valve to let air out? Should I use the shitty jack from the spare tire well (only one I have) to tilt the passenger side for more air to come out?

I need to start registering the car tomorrow & possibly undergo inspections & don't want to harm the car by driving it, if there's still excessive air in the engine coolant system.

I'll obviously check the coolant levels after the car cools down over night & top off, if needed, but concerned about radiator valve.

Thanks from paranoid Dan!

 

I worked on a Gen 2 once that had been in a wreck, and I searched and searched for that Allen-head radiator bleed, until I realized they just put on an aftermarket radiator that didn't have one. Still managed to get a good fill, with some patience.

 

The radiator bleed is there - the thread is just stripped. From what I understand I would need to disassemble the steel frame under the hood to gain access to it & pull it out using pliers together with some other instruments. I'd look into that once I get my hands on a replacement valve (part # 1641720290) from Toyota. But for now I'm anxious about possible air in the system

 

Jack up the passenger side a bit, leave the radiator cap off, and bleed it that way. The air should come out eventually.

Once you get to the point where no more bubbles are coming out of the radiator mark the center of the overflow tank (like with a sharpie) and fill to that point, fill the radiator and close the cap, and drive it. Every day check the level in the radiator and overflow when it is cold, and top off as needed. In a couple of days all the air should be out and you will no longer need to add more fluid.

 

This is exactly how I did mine and it's been fine over the past ~year. I may have had to top it off once after the initial bleed, but since then the level has been steady and my coolant temps are right where they should be.

It did take a long time, but from what I understand that's pretty normal for these cars. It probably took me around 2 hours to get the whole thing bled, between the initial fill and then warming the car up to get the rest of the air out. Admittedly, this was in the middle of winter (because of course that's when the coolant valve went out) and I decided to do a complete coolant replacement since it was probably about due.

 

My daughter's 2007 has 162K miles and DTC P1116 and P1121 were logged. This is the first time I had to replace the engine coolant control valve and the experiences shared on this thread were very helpful.

I bought a replacement valve from eBay for $89 (incl. shipping) which came in a Toyota/Lexus box and had the correct Toyota part number label. However the actual valve had no Denso markings on it, unlike the original valve, so I t hink this new valve is actually no-name aftermarket.

I removed the driver's headlight assembly for access which required loosening the front of the left front fender liner and the bumper cover. It is pretty easy to remove the headlight assembly and I recommend that. I needed to remove the headlight assemblies anyway because I wanted to replace the plastic wire sockets leading to the headlamp bulb connecting pins as the sockets were partially melted. I replaced them with ceramic sockets purchased on Amazon.com. The headlight assembly clear plastic surfaces also need to be refinished and I am going to have a local body shop work on that.

As other posters noted, it is much easier to remove the hose clamps with the cable driven tool, especially the lower of the two hoses that fit into the side of the valve. Rather than try to remove the hose that attaches to the bottom of the valve, it is easier to remove the hose where it attaches to the pipe at the bottom of the coolant storage canister, then remove the valve with the bottom hose attached, from the car.

I drained coolant by only using the drain at the coolant storage canister, and got around 4 quarts out. Perhaps another 4 ounces spilled into a rectangular drain pan while removing the valve, I used rubber plugs to plug the hoses.

I ran the coolant heat recovery pump several times by connecting an ammeter to the switched pins of the CHRS relay socket, to fill the coolant storage canister. The current draw was around 1.8A before the coolant started to reach the pump, then increased to 4A when the pump actually was moving coolant.

 

thanks everybody ....for posting on this thread and so many others throughout the years...long time lurker ...first time poster...i have 4... 2nd gen priuses...used to have 5...the first one i had i got off the lot in 07 with zero miles...300k+ later it finally died...been lurking here the whole time...LOTS of good advice !


i recently got the P1121 code too and replaced the coolant Control valve... But I used a Chinese knock off from o'reilly's autoparts "Dorman OE solutions "... Bad idea!... it worked for about a week and then right out the blue crapped out again cold air coming out.... I fallen into this trap before trying to get away with the cheap Chinese knock off but bad idea... gonna go to the Toyota dealer and get an OEM part tomorrow

 

I don't know what prices are like right now, but when I bought mine the OEM valve was only about $10 or $15 more than the knockoffs. Absolutely worth it to not be stuck without heat in the winter for a good long time.

 

where is your video? I see a reference to it, but can't locate the file.

Thanks

 

I did this yesterday and took the 3 way valve out through the top. You don't have to go through the headlight but its very accessible that way. See ref video

for orientation of the valve to fit through the top after propping up the inverter a bit. I did access the bottom pipe from the bottom.
I used this as an opportunity to change the fluid. See

On how to run the pump in the valve to bleed the system. You don't need an amp meter and can just use a jumper wire. It took about an hr to bleed the system and get all the fluid in. My bleed valve was not working though.

SM-G960U ?

 

I don't know what got into Toyota at around this era, but several parts are unnecessarily hard to replace because they have a large strangely shaped bracket attached to a plastic case which must be maneuvered through a tight path. The coolant control valve is one and the battery fan is another. If the bracket had been held on with a bolt/washer/nut sort of connection through a hole in a thick plastic flange then taking the bracket off would have been a good option, making the part smaller (effectively). Unfortunately they also were on a binge of "metal screws into plastic for bracket attachment", and that sort of connection has a nasty tendency to break when disassembled, either cracking the case or stripping some of the plastic threads out with the screw. Worst case, the screw strips all the threads and also cracks the case! Anyway, having worked on both of these parts, I really wish the designers had made the bracket a part that first bolts to the car, with the valve/fan bolting/unbolting to/from that, which would have made servicing them much easier.

For the next generation those crazy brackets were gone. They ditched the thermos and coolant control valve altogether, and the battery fan just bolts down to a flat surface.

 

In Toyota's poor engineering defense, the Gen 2 is more reliable than Gen 3

 

Yes, but not because of those stupid brackets.