check engine light + soft whirring noise

Hi everybody,

2007 Prius, just under 130,000 miles on it, still on the original hybrid battery, had the 12 volt battery and inverter pump both replaced last year. I live in the Coachella Valley where it is HOT right now.

Last Wednesday, July 22, my check engine light came on just as I was returning from dropping off my broken cell phone at the phone repair shop. The phone was not fully fixed until Monday so I couldn't call my usual mechanic, but I did stop by Auto Zone to get the codes read. It showed the codes were P1121 and P1122. Indicating an issue with the coolant flow control valve.

I drove the car on Friday and it was driving fine but that's when I noticed the soft whirring noise recurring constantly as I drove. The whirring noise lasts about 4 seconds and recurs about every 5 seconds. I did some internet searches and it seemed like the noise could be connected to the faulty coolant flow control valve.

On Tuesday morning I finally dropped off my car at the mechanic shop. They called me later to confirm the problem was the coolant flow control valve, and he quoted me a total price of $930 to take care of it (including a $150 diagnostic fee). I agreed, and picked up the car this morning. But I have two problems:

1. The invoice they gave me is inconsistent. Under Labor, it clearly says "coolant flow control valve, remove & replace" but under Parts it lists "engine auxiliary water pump" which -- according to several internet searches -- is definitely NOT the same thing.

2. On the drive home, the car is still making the exact same noise as before!

I did call the repair shop again (worth noting they are extremely busy these days) but I did not talk to the same guy I had been dealing with before, and he seemed confused. He tried to tell me that the coolant flow control valve and the auxiliary water pump are basically the same thing because they are part of the same system, but I'm not so sure.

Can anybody out there help me understand what the heck is going on with my Prius?

 

Yes. The reference number for the part is 1629021011. Which, from my internet research, does seem to match the engine auxiliary water pump.

I had considered it might have something to do with the ABS. Obviously I'm hoping not. For whatever it's worth, during the Auto Zone check, the ABS got a pass, as did everything except the emissions.

Also, I don't know if this is related or means anything, but the whirring noise cycle continues for a minute or so after I turn the car off, accompanied by some soft knocking sounds. It's hot, so I'm blasting the AC every time I drive the car. Could that have anything to do with any of these noises?

Thanks for your response. I'm starting to wonder if I should drive out to the mechanic shop tomorrow morning, just to clear up the discrepancy with the invoice. I'd like to know which part actually got installed!

 

I appreciate the reply but I'm getting more confused. Getting back to the core problem with the invoice -- the codes on the car (P1121 and P1122) showed a problem with the coolant flow control valve, yes? And the mechanic confirmed over the phone that the problem was the coolant flow control valve. And in the Labor section of the invoice, it says "coolant flow repair valve remove & replace"... but then the replacement part on the invoice says "engine auxiliary water pump" with the reference number I gave.

Before I drive down to the repair shop again to ask about this, I'm trying to get an idea of what happened. Does the invoice contain a mistake? Did they replace the wrong part?

As for the noise... as you know, the Generation 2 Prius is a noisy car. It makes all kinds of mechanical noises. But I first noticed the semi-constant whirring noise on Friday -- the first time I drove the car after the check engine light came on. I'm used to the noises my car makes and this just seemed different. Now maybe the noise had been going on for awhile and I just didn't notice it until the check engine light came on. My gut feeling is that I think I would have noticed it before if it had been going on for awhile. But at this point, it's hard to be sure of anything.

 

Thank you very much for the response. Apparently I'll have to visit the repair shop in person to get their attention about this error.

If the whirring noise is the brake actuator, what are my options for repairing the thing? Are there any other warning signs I can look for?

I've been using this repair shop for over 20 years, and I do think they are honest, or at least they used to be. But as this place has gotten more and more successful and busy, their communication skills have fallen way off and their prices are getting very high. The owner has made it clear to me he doesn't like working with hybrid cars and he won't touch anything related to the hybrid battery.

And maybe it's a petty thing, but they used to give me free rides to and from my house, with their own driver, but a few years ago they switched to using Lyft, and now the owner wants to start charging me for the Lyft rides.