P1121 one week after main water pump replaced

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by lcooper, Feb 7, 2011.

  1. lcooper

    lcooper New Member

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    On my 05 Prius (65K miles) I recently had my local Toyota dealer replace both the inverter water pump (for free per recall) and main engine water pump (~$500 based on their recommendation because of some coolant leakage). 1 week later, I got the P1121 code coming off and on intermittently. I appreciate all the posts to date on P1121.

    My question: does it seem like more than coincidence that this would happend so close to each other? I don't like the idea that Toyota acknowledge that the coolant control valve is faulty with a TSB that only covers it under 36K miles. Should I think of this part (or perhaps its the sensor) as just another routine maintenance/replacement item?

    My dealer says that the work they did is not related to P1121.

    Thanks for any and all thoughts on the matter.
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    DTC P1121 does point to the engine coolant flow control valve having failed. The dealer tech's work on the two coolant pumps should not have negatively affected this valve. It's reasonable to think of the part replacement as part of the on-going price you pay for owning a highly complex vehicle.
     
  3. lcooper

    lcooper New Member

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    Thanks Patrick. I thought I saw one post saying if one of the coolant levels was low (or perhaps wasn't properly bled) that it may affect the coolant control valve. Just searching for answers I guess.

    Cheers.
     
  4. seilerts

    seilerts Battery Curmudgeon

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    The work they did involves the cooling loop that contains that valve. At the very least they should check for free whether or not the system was filled and bled properly. I don't believe in coincidence when it comes to mechanical problems on these cars.
     
  5. lcooper

    lcooper New Member

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    They did finally offer to do just that (check their previous work). Initially when I didn't know the code and just got the warning they were telling me that pulling the code would cost $150 if it wasn't related to their work. So I went to a friend's and we figured out it was a P1121 through his little device.
     
  6. jdenenberg

    jdenenberg EE Professor

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    I had a p1121 code just after a coolant change in my 2004. Adding more coolant to the ICE coolant loop cleared the problem. My guess it that the coolant acts as a lubricant for the valve so a low ICE coolant level can cause the valve to stick.

    JeffD
     
  7. kleber

    kleber New Member

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    I brought my 2005 Prius in for the free recall replacement of the water pump. 2 days later the warning light came on. I took it back and they identified it as the p1121 code. They topped off the coolant level and said it was probably a bubble in the system. No charge. They warned that if the light came back on, it would mean replacing the coolant control valve sensor at the cost of 100+ for part and 297. for labor. The light came back on the next day, then off, then on for a couple of days. They told me to bring it back and they would recheck the code before ordering the part. Same p1121 code. They wanted me to pay ahead for the part before they ordered it. I protested that this seems like a problem as a result of their recall work and it should all be free. The part came in yesterday and they are replacing it tomorrow but I will have to pay. They insist that it is not related. I really don't believe them and just lost faith in my dealership. Has anyone been told that it is related? I have 82000 miles on my car and had no problem with my cooling system before brining it in. Please reply!
     
  8. jdenenberg

    jdenenberg EE Professor

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    First, there are two independent coolant loops. You had a free service on the Inverter coolant loop where they replaced the electric coolant pump. If you also had them replace the Internal Combustion Engine (ICE) Coolant or the mechanical coolant pump then they also worked on the ICE coolant loop which is where the suspect valve is located. These are completely independent systems.

    Low ICE coolant can cause a p1121 code as the ICE coolant acts as a lubricant for that valve. Check the coolant level in the ICE loop and top it off if necessary. If you continue to get a p1121 code, you will need to replace the valve at your cost and only a dealer or an experienced independent hybrid repair station can do this job for you.

    JeffD
     
  9. White Gold Prius

    White Gold Prius Junior Member

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    I'm having exactly same problem right now. I can't remember if I got the CEL with p1121 before or after the recall job but it was very close.

    My noob questions is how easy it is to check and add the ICE coolant and what kind?
     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    See my post #22 here which explains how to drain and replace engine coolant:
    http://priuschat.com/forums/gen-ii-...shooting/30813-changing-engine-coolant-3.html

    Since you just want to check the level and add, you'll only be doing a small subset of this activity. You need to remove the plastic cover over the radiator for access to the radiator cap. Remove the cap and fill the radiator fully, then fill the overflow reservoir to the top mark engraved on the side of the reservoir.
     
  11. kleber

    kleber New Member

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    My dealer decided that the recall work probably did trigger the problem. They did not charge me for the work after all.
     
  12. Stomper88

    Stomper88 Member

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    I am also seeing the P1121 code come and go. It started about 2 months after the inverter coolant recall service.
     
  13. seilerts

    seilerts Battery Curmudgeon

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    Check your coolant level (expansion tank) and check for a leak in your engine water pump (pink splotches on top of the A/C compressor)
     
  14. Stomper88

    Stomper88 Member

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    When it first happened, I checked the coolant and the reservoir had some, but it was just under the L. So I topped it off. The level hasnt changed after that.

    Since then, the P1121 comes and goes. It usually comes on when I drive for more than 20 minutes at a time, then goes back off a few drives later.
     
  15. seilerts

    seilerts Battery Curmudgeon

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    Next thing to check is physical damage to connectors at the thermos, underneath the driver side headlight.
     
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