CEL Hell - 2007 Gen 2 Trials and Tribulations

Hello Fellow Gen 2 Prius Owners:

I bought a 2007 Prius last December as a daily commuter. I drive about 100 miles per day, so I wanted the high mpg and reliability that the Prius has become known for. It had 150,000 miles on it when I got it, and I have to say I've been pleasantly surprised at how much I like it, and it's versatility at everyday tasks. BUT...

Within the first day of getting it, I started seeing the CEL come on, and it's been on/off ever since even after a significant amount of work from me, and several trips to the dealer. See my timeline below of the codes and what's been done:


December 28, 2018
P2601
Dealer said it was heater control valve (HVAC), replaced it


Jan 13, 2019
P1116 - Coolant Temperature Circuit Stack
Read some posts here and also watched some videos online
Replaced inverter coolant pump - DIY
Reset the CEL

Jan 18, 2019
CEL, light came on - P2601
Took it to dealer on Jan 25, 2019
They replaced the CHS tank pump - ~$400
Reset the CEL
Light stayed off for a few weeks


Feb 15, 2019
CEL light came on
P1116 - Coolant Temp sensor/coolant storage tank
Dealer wanted to replace CHS storage tank, estimate $1675
Declined to do it at that time
I reset the CEL light
Stayed off for a couple of weeks


March 4, 2019
CEL light came back on
P2601
Coolant Pump Performance Control Circuit Range

TODAY - still driving with the CEL on, and code P2601 is what the system is throwing when I check it. The car seems to drive OK, no signs of trouble with it. I do hear the pump run right after I shut the car off, and again when I start it.

My question is, do I really need to replace the CHS coolant tank and sensor like the dealer said? I've done basically everything else (heater control valve, inverter coolant pump, and CHS tank pump). I just have a hard time believing I had to replace every major part of the system and the car really doesn't have that many miles in the scheme of things.

If I do need to replace the CHS coolant tank/sensor, should tackle it myself, or is this one best left to the dealer or other trusted shop? I did the inverter coolant pump myself, which involved tearing a big part of the front bumper apart to get to it, and it wasn't that bad.

Let me know your thoughts, experiences, and two cents worth if you have time to read this somewhat long-winded first post. Thank you.

 

On December 28, they replaced the 3-way control valve. Dorman 601-021 (replacement part from Amazon). It was brand new.

 

Yes, a non-Toyota dealer did the work. So you recommend checking the valve they put in to see if connections are correct? I suppose it's possible they installed it wrong. The person doing the work was not at all familar with Prius, as I found out when I picked it up after repairs.

 

Wow, that looks pretty involved. But I agree that's a better option to start with than just replacing the whole chs tank without eliminating all other variables first. I will give it shot this weekend. Thanks!

 

Hi Patrick. Quick update, I actually haven't tried to drain coolant and replace yet, per your posts #22 and #42 from previous thread. When I do, I am wondering if I need to bleed the system using the bleeder valve located on the right side of the engine compartment. Is this all part of the coolant system, or is there a separate system for the inverter coolant? Thanks for your help.

 

Hey Patrick, it's now several months later and CEL has never stayed off. Car is running fine in my opinion. Now the latest code being thrown is P1121. A lot of people on this forum have say that's the three way control valve. That was just replaced when I first got the car back in December/January.

I tried checking for air in the lines today, cycling the CHS pump several times for 30 seconds while adding fluid in through the radiator cap. I didn't see any bubbles and fluid did not go down at all. So, I am assuming there is no air in the lines. This would make sense because the dealer replaced all coolant when they put in the new CHS pump.

Any ideas for what to try next? Thanks for all your suggestions thus far.

 

Thanks, Patrick. Is it possible that the coolant control valve was installed wrong in the first place, meaning they switched up a coouple of the hoses coming into it? I looked and tried to follow where they went, but it's tough to see. Would the car even be able to run right if that happened? I had a former Toyota Technician tell me I should check that. Have you ever heard of that happening? See the below exlpanation from the tech:

"1. Check the position of the hoses; the hose out of the bottom goes to the coolant heat storage tank. The hose in the middle goes to the engine and connects to the cylinder head and the top hose goes to the heater water pump and then to the heater core. The top 2 hoses are easy to mix up."

The bottom hose looks like it does indeed go to the CHS tank, but I can't see for sure on the other two.

 

UPDATE: Around Sept 15, I installed a new three way coolant control valve (OEM Toyota, not aftermarket). I also then refilled the coolant via the radiator, running the CHS pump via the relay for 15-20 seconds at a time. The install process was about 2 hours due to the tight area and the spring hose clamps. The bleeding process was about an hour. I then re-set the check engine light, and so far so good. It's been almost two weeks and the light did not come back on yet. Thanks everyone for their comments and help. This was a bit out of my comfort zone (que the ominous music, anquished facial expressions, and expletives while coolant was leaking out of the car and I struggled with those darn hose clamps), but in the end I feel pretty good about having completed the repair myself, and solved an issue that wasn't fixed by multiple trips to the local Toyota dealer.