Coolant flow control valve/P1121 and a buzzing noise?

Replace the valve and see if the noise goes away. The valve failure does make a strange sound in the engine bay

 

When my valve failed it was more like a rhythmic clunking noise. I agree, replace the valve. The error may reset itself and the CEL may go out, but that will be temporary. You probably want to do this before heating season.

If you DIY, be sure you know how to run the CHRS pump and properly bleed the radiator. I spent about $80 for the valve and $40 for coolant (optional).

 

What is dealer cost to replace valve? I have 2004 Prius at independent shop and they want $471 including tax.

I had a check engine light and code is 1121. It makes that whirring/buzz sound every 5min or so when driving, like the valve it trying to actuate, but it is not working right so it keeps trying.

 

call the dealer and ask the service dept.

 

I did and they said they can't provide any pricing unless I bring the vehicle in for them to diagnose. They also told me it there would be a charge to diagnose.

 

Why would you need them to diagnose when you know what you want replaced? Do they diagnose your car when you go in for an oil change?

 

I do not know, I don't work there. They did tell me that there are many reason for getting a code E1121, not just the valve. I'll call another dealer in the area to see what they say.

 

They are correct, low coolant can cause that problem.

But what I don't understand is how they won't quote you a price to replace a part you want replaced. say "let's assume it's bad and I need it replaced...how much would that cost?". Why can't they give you a straight answer to that?

 

Sorry for wasting everyone time. I've gathered the repair cost ranges from $300-$550 depending on the shop. I have come to understand the dealer wants ~$100 to check to tell me if it needs replacement which is why they won't tell me on the phone.

 

It's not a waste of time, I just don't understand dealer logic.

If you have some tools, you can do this repair yourself pretty easily. The part will cost you around $80 online and you can do it in about 2 hours. Youtube has a few good videos on this.

 

You can do it the same way the dealer does it, by clamping the hoses. Very little coolant will be loss and it's very fast to complete.

You can get really good hose clamps from Sears "craftsman stuff".

 

That is my concern as well. I've replaced the 12V battery multiple times, done oil changes, diagnosed and repaired the PCM in the A/C fan controller, but this repair sounds both tedious (hard to reach) and requires the care to properly bleed the coolant. Plus it is 110F in my garage when I have time to do the work.

 

P1121 doesn't affect the reliability of your car. You can put it off until it cools down before you tackle the job. Only problem it "might" give you, is your heater might not work properly in 110 degree heat.

 

Ditto this. I put mine off for most of a year, gathering tools (MiniVCI, long nosed pliers for clamps, and small tube for the bleeder valve), waiting for good weather, and reading the procedure for bleeding. If it's time to change the coolant, might as well drain the system (add $40 for new coolant). Many DIYers report varying degrees of success with clamping the hoses--some get a real mess!

 

Some of best hose clamps I've seen are at Sears. Craftsman stuff......can't really make a mess with the proper tools.

 

I have the replacement part (1667-21020) in hand now and weather is cooling so I am now getting tools ready.
Is this the definitive thread of the ideal replacement process:
P1121 - Coolant Control Valve Replacement (with pics) | PriusChat

I want to minimize coolant leakage as the existing coolant is at 50k so I'd rather not replace it all.

Do I need one craftsman hose clamp tool or three? I understand the tool is just for opening closing the existing clamps in tight spaces and is not used plug the hoses. So if I want to minimze leakage I need clamps too? Or do I use the tool to add/remove clamps to plug hoses?

If I do it just right and get lucky will I need to use the coolant air bleed procedure?

Really I'd rather not replace the valve at all, but I don't like my 'Check Engine' light being blocked by code P1121