P1121 - Coolant Control Valve Replacement (with pics)

Yep. That would be a good plan.

 

Thanks Stomper for this thread, that cable tool was a lifesaver. I replaced the valve on my 06 in Dec 17 and this thread was indeed a lifesaver. Wanted to thank you sooner, but forgot my password and then forgot by the time I reset it.

However the stupid OEM replacement valve seem to have failed again less than 18 months later. Not sure why it is so premature, but I will do this one last time with OEM parts. The prius has almost 200k miles on it, but has been serviced really well wit coolant replacements, etc. Had the waterpump replaced in August last year though as it started to seep.

Overall not bad given the miles and years, but a bit concerned given the rapid failure of this part. Was hoping to get a few more years and not too many miles out it. My daughter drives it now with lots of shorter trips vs my old long commute.

 

I did this repair just recently. Thanks to all for all the tips, it really made things easier. I elected to move the inverter a few inches, without disconnecting anything, to gain access to the valve.
I was curious to see why the valve had failed. I applied 12v to the motor and the valve turned, so I suspected the sensor. I took the sensor apart and found a dead spot on the resistance element. It looks like once the sensor starts to go bad the car will move the valve back and forth to try and hit the correct position, wearing out the sensor more quickly. You can see the dead spot on this picture.

 

I also just got this DTC P1121 code after having let my 2009 Prius sit in the garage for a few weeks without starting. Found the battery dead just before I needed to smog it. I jumped the battery and all seemed well until the check engine light came on the way to the smog station. I went back home and used my OBD2 LX adapter with Torque Pro app to see what code it was and I cleared it. Light came back a couple of days later so I took it to the dealer for a free diagnosis. They wanted $614 to repair and replace coolant. I'm old now so was hoping not to have to give in to the dealer so I printed the TSB on this issue & took it to 7 local shops for an estimate. The lowest was $340, highest was $649.
After researching and viewing the videos I found the confidence to tackle this. Part was $101 and I had all the tools.

Procedure:
Remove black shroud on top.
Jack up the left side and remove 3 screws to fold & wire back the wheel well shroud (see pic)
From there you can clamp the hose coming from the bottom of the coolant thermos. Leave this clamp on for the entire procedure, only take off after you have the valve and all the hoses fitted to the new valve. (see pic)
Raise up the invertor (see pic)
Muscle off the clamps, I used various vice grips, and channel locks (see pic)
Remove electrical connector by pushing in on tab.
Plug off the hoses with...(wait for it) wine corks! They fit perfectly. I also found some smaller corks for the valve itself. (see pic)
Ratchet off the 2 bolts holding the valve.
Pull it out from the top by using the orientation shown it the picture. Its the only way to get it out from the top.
Reverse the procedure for the new valve.
After all hoses are connected. Remove clamp from bottom hose.

What I learned:
I was able to get this done in about 2 hours & I only lost about 1/4 cup of coolant.
You can see in the picture of the old valve how the interior white gate has gotten stuck halfway.
I thought for sure since my 2009 was the last of that generation, that they would have fixed this part after having known about if for at least 3 years previous. Apparently not. Thanks Toyota. This should have been a recall.
If you get this DTC, you must replace the valve in order to pass smog. It will keep throwing a permanent code until you do so. Just clearing it will not remove it as it will still be detected by the smog service center's scanner. At least this is the case in California.

 

I'm not familiar with this, but:

It took you $110 for the part and two hours DIY labour (and that's with no previous experience doing it, no lift, etc).

And dealership wanted $614 to do the same job?!

 

Haha...I know right...

I rarely drive this car, and it sits in the garage a lot since the pandemic. It only has 62,500 miles so I was a little shocked that this valve failed so soon on a 2009 which is the last year of Gen 2.

They also found a little dried coolant on the water pump pulley, so I'll probably be doing that soon too.

 

Thanks Prius Chat and everyone for great troubleshooting write ups. I’d like to add on p1121 that my code didn’t go away because the gear was in the wrong position.

I tested its function prior to install with a 12 volt battery and leads. I must’ve left it in the wrong position because I couldn’t get the heater to blow hot.

I fixed this by disconnecting the harness and powering the pink and black wires. If you reverse polarity, the motor spins the other way. You could also use this to test the function with the part still installed. If it’s sticking, you could probably increase the voltage to try and dislodge it.

So basically if you install the CCV and still get the code, you’re either low on coolant or have the motor bottomed out in the wrong position

 

That's a peculiar story. The valve includes a position sensor, so the car does know which position the valve is in, and can move it to the position it wants. So I don't doubt that the story happened as you say, but I think there must be something more to the explanation.

In fact, the usual problem with these valves in the first place seems to be the position sensor, not any other mechanical failure of the valve itself (see #143). That's the same way the HVAC servos eventually flake out, which work the same way (and back in Gen 1 that list also included the steering and the accelerator pedal).

 

Interesting. This worked for me and the code hasn’t been back since I force the motor to bottom out in a new position. Perhaps the water pressure kept if from operating properly?

It’s worth a try I’d say. The car does have 220,000 miles (if the computer even keeps track when the combo meter comes and goes) so ever part is kind of suspect at this point.

The coolant also now travels to the thermos tank after I turn off the car.

 

P1121 a few days ago. Techstream showed no other codes. Coolant level is normal and the strange noises the car used to make from the 3 way valve are now gone, so I believe it really has failed. Reviewed service records and apparently this valve had never been replaced, seems due at around 130K. Ordered one from Toyota of Tustin - for some reason they were $85 less than Pasadena Toyota. Well, not quite, because it was $11 to ship -I didn't feel like driving that far for the part. A flexible hose clamp wrench is on order too.

Have now watched 5 videos on how to do this but none from anybody who had done one before. Well, maybe one, he was vague, but he was doing it a different way this time, which involved removing the radiator bracket. Can somebody point me at a video by a person who has done a bunch of these and actually shows how to do it quickly and efficiently? (Youtube is like that, way too much first time stuff. Can you imagine what their medical videos would be like? "This is my first time doing kidney surgery, I know they are back there somewhere, so I started by just cutting down the center of the abdomen and will now move stuff around until I find them.") Only one of the videos showed the removal of the bottom hose, they had drained the coolant and released the other end of the hose at the thermos. In that case they pulled the valve out before removing that hose.

I do not want to drain the coolant, it is still in good shape. However, given the ages of the hoses, don't want to clamp them either. I plan to use corks in the ends of the hoses right after they are pulled off. This worked well when changing the inverter pump, only about half a cup of fluid leaked in total. Here though there is a 3 way valve instead of a stalled 2 port pump, and I'm guessing that fluid may pour out of the valve from one of the other hoses which are still attached. One video (by Lev something or other?) also plugged the ports on the valve as he went with short bits of hose with bolts stuck in them. Seemed like a good idea to me, since plugs (corks) into the plastic might crack it from inside pressure, whereas the bits of hose will apply inward pressure as usual.

There seem to be 3 bolts holding the inverter. People remove the front two and tilt the inverter up to obtain about 1.5" of lift on the front bracket above the radiator bracket. They don't go higher because of the back bolt. Why? Is there some reason the back bolt cannot be loosened a couple of turns to allow 2 or 3" of lift? Maybe not enough leeway in components on the bottom of the inverter?

 

There's the thing with youtube:

Some people will need to do some job on their car. They'll be sensible about it, look up how in the manual, go do the job, it goes fine, and they move on to their next thing. They don't really think about posting a youtube video for it, or if they think about it, their thinking goes "why bother? the steps are in the manual and the job went fine, what would I be adding?"

Somebody else will need to do the same job, jump into it unprepared, end up improvising their way out of a bunch of self-inflicted setbacks, and when they finally emerge victorious after figuring out what they didn't look up first, will feel like "the internet needs to know how I did that!" and poof! you've got youtube.

 

After a short drive today it seems to have temporarily fixed itself - the noise is back and the CEL went out. I'm still going to replace that valve though.

 

I see that redwald used corks to plug the hoses (except maybe the bottom one, which was clamped). I will use plugs too, but rubber ones. Home Depot sells slightly conical rubber stoppers in various sizes which worked well for the inverter pump hoses. This may not be the right size one for these hoses, but is representative:

Everbilt 11/16 in. x 1/2 in. Black Rubber Stopper 808208 - The Home Depot

I would be afraid to use cork (as in from a tree) lest little chunks break off and later play havoc with a pump, a valve, or get stuck in some narrow engine passageway.

 

So I did this over the last couple of days (ran out of daylight yesterday.) The car had sat for 2 days before doing this, to allow the thermos's contents to cool (which turned out to be a good idea, since some spillage from there occurred.)

I did it basically as outlined by redwald. Marked the top hose with a zip tie, and used those rubber stoppers instead of corks. Also used a cable driven hose clamp tool. However, these issues were encountered:

1. The rubber stoppers worked great for the hoses but they were bad for jamming into the plastic outlets. They would go in and stop the flow, but the slightest bump and they would pop right out again. Apparently the interface between the rubber stoppers and the slick plastic was, well, just too slick. Not enough friction to hold them in well.

2. The top stud broke off. The nut was super hard to turn and when it snapped off it was evident that the nut was at an angle with respect to the shaft. "Luckily" about 3mm of the stud remained, and that was enough to act as a peg keeping the top of the bracket from being able to move laterally. With the other bolt screwed in firmly it doesn't look like it is going anywhere.

3. Could not get the darn part up through the hole in front of the inverter (yes, it was raised with 2x4s) no matter what position it was in, so eventually I gave up on that, unhooked its bottom hose, and dropped it out the bottom. Then put the new one in from the bottom.

4. One of the bolts holding down the inverter did not want to go back in. Those things are not normal bolts, they look like a cross between a self tapping metal screw and a bolt. Replaced both of them with M8 bolts, 20 mm long, with one washer each from my pile of random washers. (Ie, I have no idea what size they were.) Those screwed in easily.

5. Collected about 16 oz. of spillage, but some more missed the container and ended up on the driveway or in concave parts of the under body shields. When topping off the coolant around 1/3 of a gallon container was used.

Burping the air out of this thing did not go according to plan. First added coolant to the radiator. The bleed valve was supposedly open (3 full turns counterclockwise, maybe not enough?) but nothing ever came out even when the radiator neck was full. Closed that bleed valve. Pulled the relay and ran the container motor shorting the top 2 pins with an ammeter, hardly any bubbles came out and it always read 3.1A. Some videos suggested that something more like 4.0A was to be expected. Yet at least a cup of coolant had leaked from it. When the car was warmed up some more bubbles came out, but oddly the coolant level in the funnel did not fall much. Maybe the expansion of the coolant was offsetting the loss into the system? When the car was turned off then it bubbled a fair amount, when the car cycled hot coolant into the thermos. Put the radiator cap back on and drove it for 10 minutes. Seemed normal enough, no odd fluid sounds, no CEL.

Anyway, right now there is no gurgling from the console when it starts or stops, and the heat works fine. It makes normal noises when it turns off. The CEL is out. I guess I will just keep on eye on the radiator for a few days and keep adding coolant at the neck if the level falls. There is probably still air in the thermos which hopefully will work its way out a little more each time the car turns off.

 

First day after: coolant in fill neck was low about 4-5". Refilled to top. Filled overflow to dot on side (or half way, but I cannot read the marks easily, so the dot somebody placed on the side is easier.) It was only a hair low. Drove it around, no problems.

Second day after: coolant was full to top of fill neck and was at dot in the overflow tank.

Stuck a funnel in, added a bit of fluid, and jumped the relay with the same ammeter. Was reading 3.4A. No bubbles at all, even after 5 tries. So I tried a different ammeter. The second one read 4.1A at first contact and had dropped to 4.0A at 20 seconds. The second DVM gave the readings other people reported.

Conclusion, no problem with the pump or bubbles, just another broken Harbor Freight DVM.

 

I just replaced the valve tonight and bled the coolant using the CHRS tank pump relay. Drove around the block carefully a couple of times. Is the CEL supposed to go off on it's own or do I need to clear the codes with a ODB2 tool? I'm in need of a smog check on this car.

EDIT: So the CEL went away when I started the car the next morning. I hooked up an OBD2 tool it shows fault code P1122.

Will this code cause a fail for smog check in CA? No check engine light.

 

You might first have to drive a couple of hundred miles to pass, even with the CEL out. It doesn't say that explicitly in the following link, but it is the case if the 12V has been disconnected:

https://www.generalautorepairsd.com/blog/2017/2/20/heres-how-to-pass-the-california-smog-check-

If you have a mechanic you use frequently, perhaps they can tell you. Heck, call a smog station and ask.

 

Is the P1122 being shown as a "permanent" code? If so, it will show that way until the car has successfully re-run the monitor test for that code and proven that the issue is fixed. There's no lazy way to make permanent codes go away, but each code will have a "confirmation driving pattern" shown in the repair manual that you can drive if you're impatient, that will nudge the car to complete the monitor test earlier than it might if you just waited.

Usually, the confirmation driving pattern is driven after you've done a code clear with a scan tool, and that erases the current monitor results for all monitors, not just the one you're interested in. Then you have to make sure you don't go in for inspection until all of the monitors have completed again.

The "drive around for one or two hundred miles" advice is approximate; generally if you do that much driving, all of the monitors will have had their chance to run by then. But it doesn't have to take nearly that long. If you have a scan tool that shows you monitor status, you're good to go for inspection as soon as it tells you all the monitors are complete. Or you can drive the specific confirmation patterns of any that haven't completed yet, to nudge them along.

 

Thanks for the replies. I just want to give an update. I drove around town for about 12 miles until my scanner showed all sections of emissions readiness as complete. The P1122 code remained, but I decided to go for the smog check anyway and it passed all categories!

 

The plugs are Toilet seat mounting bolts.


I'm trying to source out an OEM valve that will ship to Canada... it Should be a $80ish usd part... and most of the suppliers who'll ship to a Canadian address want 2-3X that... Crooks.