check engine light: codes p1116 and p1121

Hi folks.

I've got our beloved 2005 Prius giving us the dreaded CEL with these two codes: p1116 and p1121.

Had the guy at Autozone give me the codes for free, and after googling around I see that p1116 is about the coolant temp sensor, and p1121 is for the coolant flow control valve.

Anyone know what my next step should be? Paying full price just to get the valve replaced would seriously injure our Dave Ramsey emergency fund (about $400, right?). I say a thread on here where a nice fellow, stomper88, gave a step by step guide for changing the valve (cutting cost way down). What about the sensor? Should I change one and see if the problem goes away, or do you think I'll need to do both? D I need to take it in to get the problem narrowed down first?

I'd appreciate any help someone can offer.

 

Added coolant and after 2 days of driving the light is out. Yay. Thanks friends - here's to hoping that was the only issue.

 

Ok, the check engine light is back on.

I took the car into the dealership to get the oil changed and they said I am leaking coolant, and therefore need to get the water pump replaced. What are the odds that it's really the pump, and not the control valve? Would they have checked for that? They wanted way too much $ to do the replacement so I have an appointment at another mechanic tomorrow to do the water pump. What should I say - should I ask him to make sure it's not the valve or something?

I also have to have him figure out why my A/C isn't cold, which as far as I can tell means recharging it, and then checking for leaks. Yay.

 

See, this is what's odd - I checked the fluid just two days ago, and it was still full from when I filled it back in March. Maybe I don't have leak at all and the dealer just pulled the check engine codes without actually checking it?