2007 red triangle check engine etc codes POAOF, P0121

hi guys, thanks for reading. my prius has 172k miles on it and has never had any issues and is regularly serviced at the dealer.

yesterday i got the dreaded red triangle and check engine light along with the temp indicator on the navi screen. i pulled over immediately. after sitting for a bit, the lights went away except for check engine. i checked the engine compartment and felt no real heat anywhere. coolant reservoir was full i drove a few more miles as i was taking a customer to the airport (i work for uber) and they came on again. after sitting for a few again they went away and i continued on to the airport. on the way back home, about 40 miles or so later, it happened again. again i sat for a few and it went away and i took it to the dealership in my town. they have always been really cool there (an anomaly i know) I never before used dealerships for anything before owning a prius) and he pulled the code for me and it showed POAOF failure to start. that had actually never happened, but was told that it doesnt necessarily mean the car wouldnt start, it can happen while running. he cleared the code, as i had recently changed the 12v battery and after reading a bit here i know it can cause some weird stuff so i was hopeful that would do the trick. so today i went out and worked again. drove probably around 50 miles or so and on the way home it happened again. back to the dealership. this time they put the main tech on it and he also got the code P0121 indicating the throttle position sensor. he took apart the throttle body and tested it and said it was showing not enough ohms or something like that (i know jack all about electrical) and that the throttle body was bad and would need replacing, also saying there was oil in the intake and it would need to be cleaned. total for everything is around $1300. I told them I would think about it and left. i tend to believe them, they even brought me back in the shop and let me talk to the tech about it. it does seem weird to me that it could just fail but i guess that is always a possibility. i had the major service done at 120k and i assume the fuel system was cleaned then? dont know. anyways, i am hoping you guys have some alternatives before i drop 13 hundred on a repair. i need my car for work so i have to make a decision relatively quickly. i had read here that oil overfill can be an issue, but havent seen much else about this problem. one other thing, the tech wasnt told the car was showing overheatng, and as i said, the resevoir was full and the radiator cap was not hot at all. when we told the tech about the overheating, he seemed surprised. so there i am, looking for a hail mary i guess.HALP!

 

Oh wow thanks. Yeah I've been reading up and it seems cleaning the throttle body is the best bet before I pay that cash. I guess that's something they wouldn't recommend if they can get me to pay for the repair without questioning. I figured he knew me better than that. Yes I'm up to date with all service. The overfilling of oil is a new thing to me. After reading about how common it is, i wouldn't be at all surprised if that was the case. If it was overfilled, might it have caused damage to the throttle body or do I just need to clean out the intake? Also, I had a maxima before and cleaning the throttle body was tricky because it would foul the maf. Is this not a problem on my Prius? The write ups I have seen here and other places just say to clean with a rag and not spray the cleaner directly in to the tb. Seems to be an easy diy.
Thanks again.

 

I assume it was clean since he had it completely torn apart and didn't suggest a cleaning. I even looked down inside and I saw no gunk, but I wasn't necessarily looking for any. I did see clean metal I believe. What would you recommend then patrick, prior to replacing the throttle body? What do you think about the tps code?

 

Also, are you suggesting the overheating is unrelated? That's my assumption also. If so, I'm wondering if I even need to worry about the throttle body right now. It seems very odd both of see things started to happen the day after I had brakes and new tires installed. I know it could be a coincidence but it does make me wonder. If coolant is low in radiator, besides just filling it what else would you recommend? It really didn't feel hot.

 

checked the coolant and the overflow and radiator are properly filled. half way on the overflow and all the way full on radiator. the mfd displayed a red thermometer symbol. the engine coolant pump was replaced when i had the 110k service done. i dont think there is an issue there. i just took off the airbox cover and looked again and the plate does look a little dirty on the edges but i was able to open it with the spring with a small amount of effort. not easy, but doable even with my left index finger. it did not appear to be sticking, just a decently strong spring is my guess. i did see a good amount of fluid in the intake body, but jc9001 said thats normal?

im thinking i will shop for a new throttle body. is there any reason to bother cleaning it now and hoping while i wait for used tb to arive or should i just jump in and find one locally and go for it today? the only reason i ask is because i cant work if my car is going to throw that red triangle and no work is also a money issue, obviously.

thanks so much for your help.

 

after reading around i see thermostat or air lock? hopefully air lock.

 

after even more reading i am suspecting it is probably the thermostat. the first tim the problem came up, i opened the hood and put my hand on the radiator cap and hose and they were not hot or even really warm.

 

And now I see that the thermostat almost never fails. At a loss...

 

Ok never mind guys the fan is intermittantly turning when the air is on low. Bad fan.

/facepalm

 

fan does switch on intermittently. my guess is worn out brushes. is this something i can replace myself easily? i have searched and see no info.

 

ok well apparently i am wrong. took it to the dealer and lead tech says the fan is operating properly and he cant get the car to repeat the problem i am having. i told them to check for air bubbles in the cooling system so i assume thats also not the issue. checked the 12v this morning and all ranges are proper, the battery is new and working. i guess my question now is is it possible for the throttle body issue to be making the red triangle and thermometer indicators light up? lost again.

 

seems strange but i'm sure you're right. thanks.

 

Cleaned throttle body and maf. Let us hope.

 

yes i did, thanks to you guys here at priuschat. thanks again.