2007 Prius P1116 code and coolant control valve issues

[mpbrisson]

My 2007 Prius is 2 years old and has 19K. It has been in and out of the dealership 4 times in 3 months...physically at the service department for 15+ days.

It started with a MIL light. I brought it in for a 20K service and they cleared the codes..said they'd taken care of whatever the issue had been. The Mil was back on the next day.

That next visit the 'coolant flow control valve' was replaced. No indication of what codes prompted this, but the codes were cleared. I took the car home. Two days later, MIL appears again.

During the next visit, the 'coolant tank sensor' was replaced. The codes were cleared. A few days later, MIL lights up again.

Over the holidays, the dealership had my Prius for 6 business days. The technician decided after much discussion and testing, that the original 'coolant flow control valve' was defective and had to be replaced again. His paperwork indicated that the P1116 code had come up 3 times since the replacement of the original 'coolant flow control valve. Took the vehicle home. Ran great for a week, but the MIL came on again.

I took it to Advanced Auto. Their code detector got another P1116 with the 2nd 'coolant flow control valve'.

I really need some advice. I bought this vehicle new. It's never been in an accident. I have never had any issues until that dreaded light came on in early November 08, and now it seems it won't go away. Am I dealing with a lemon now? Do I try another dealership? Do I call Toyota Corp?

Is this particular issue/code causing damage to the engine as it continues to malfunction? Every time I turn the vehicle on now, I'm looking for that light. It's driving me crazy. I love my car, but I don't know what to do. I would appreciate any advice.

[dogfriend]

Reading the description in the manual, the P1116 code indicates that there is a problem with the coolant tank outlet sensor. Did they try replacing the sensor? Edit oops it looks like they did. Perhaps the wiring is making a bad connection.

See attached pages.

P.S. It should not cause any damage to the engine.

[mpbrisson]

Thanks dogfriend...given that the current technician has not come to that conclusion after 4 visits, do you think it's wise to try another dealer?

The problem is this dealer is already 1.5 hrs away, the next closest is 2, the next is 2.5. This is total drag. I've put 1000 miles on the car just trying to get this straight.

[dogfriend]

Yes, maybe a more experienced tech would also check the wiring connectors and would also realize that the car must complete two driving cycles before the MIL (malfunction indicator light) is lit. That is why they think that the problem is fixed, but it comes back the next day after the second driving cycle.

AFIK, the purpose of the sensor is to verify that the coolant pump and reservoir are supplying hot coolant to the cylinder head prior to the first start of the engine. Even if it is not, it won't damage your engine. It may cause the emissions to be higher than normal because it will take a little bit longer for the engine to warm up.

[mpbrisson]

Thanks for easing my worries about any possible engine harm.

...so the MIL light was on for less than 24 hrs this time. I spoke to the dealer this morning to make them aware.

...what are the chances that this code is popping as a result of the computer's history, and what is the likelihood it will clear itself after a number of cycles???

[richard schumacher]

If it doesn't come on again you're good. But for any future problem take it to another Toyota dealer. It looks like you didn't enjoy letting the first one use yours as a learner...

[CheapA55]

I got the same problem with my 05 Prius.

1. I took it in to Toyota Central in DT Los Angeles, they changed my coolant check valve and they charged me 450$ due to it being out of warranty.

2. The check engine light came on again. They bleed the coolant supposedly.

3. The check engine light came on again. They changed the water pump, that was still in warranty.

4. The check engine light came on again. Now they know that there is still a Air bubble in the coolant system, but they do not know how to bleed it. They said they are calling Toyota Corp.

I can't believe that they do not know how to bleed the coolant correctly. After they told me about a air pocket in the system, i found out how to bleed it in 1 minute online.

I called Toyota Corp at 800-331-4331 and i now have a case manager team working on this problem. I should get a call by tomorrow from my case worker.

[SteelerJim]

I wonder if there's an epidemic going 'round. My 2007 Prius (Touring Ed, 49.5K miles) had the "Check Engine" light come on yesterday. I made an appointment at the Toyota dealer and continued driving the car. By the end of the day, the "CE" indicator had turned off. I took it in today anyway (to a dealer in Long Beach) and they told me it was the same error code as reported in this thread. They told me the coolant valve is "sticking" and it would be $450 to replace it. I declined, wanting to find out more information. I'll be interested to see what your Toyota case manager says, CheapA55.

[mpbrisson]

My water pump has not been replaced yet....but I have read before about problems with air being bled out of the cooling system.

I have also contacted Toyota and have a case manager. I am going to be contacted by an agent in my 'region' by the end of business January 23rd. I will let you all know the outcome.

My MIL light has been on 3 times since my last appointment over the holidays. It's currently been lit for 2 days. Depending on the response from the agent, I bet I'll be back at the shop sometime next week.

[Mike Dimmick]

Originally Posted by dogfriend

Reading the description in the manual, the P1116 code indicates that there is a problem with the coolant tank outlet sensor. Did they try replacing the sensor? Edit oops it looks like they did. Perhaps the wiring is making a bad connection.

See attached pages.

P.S. It should not cause any damage to the engine.

Just to state that this is the 'coolant heat storage tank sensor', i.e. the thermos. The sensor is supposed to tell the computer that it's getting hot coolant back from the thermos. The code is logged if there is less than 1 degree Celsius increase after opening the valve, or if the engine coolant sensor reads more than 25 degrees C higher than the thermos outlet temperature sensor.

If this doesn't happen, chances are pretty good that the sensor has stopped working. It can also indicate that the coolant isn't flowing properly due to a blockage. There are also three other codes relating to this sensor - P1115 indicates an intermittent open circuit or short, P1117 indicates a permanent short circuit, and P1118 indicates open circuit. If the valve doesn't open properly, it should log P1121 (Coolant Flow Control Valve Position Sensor Circuit Stuck). Codes P1120, P1122 and P1123 indicate problems with the valve position sensor.

The more I read about this car, the more I think you should just do diagnostics by reading off the codes and following the troubleshooting procedure for that code in the manual: for pretty much every system, there are sensors to confirm that the system is operating correctly, and there are electrical checks to confirm that the sensors are working properly.

I'd make sure they're actually checking the right sensor.