Red Triangle of Death, Codes P1116, P1121

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Eric Seres, Jan 6, 2025 at 5:07 PM.

  1. Eric Seres

    Eric Seres New Member

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    2008 Prius
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    Hi all,

    My 2008 Toyota Prius has had the CEL on for a bit now, and had the red triangle of death come on today at work.The internet suggests the red triangle is often a HV battery problem, but those codes didn't pop up. I ran for codes and got back P1116 and P1121, both seemingly related to the coolant flow valve and coolant levels according to posts on this site. I topped off the coolant and the oil (it was on the low end too), but am afraid to drive the car as the internet says not to drive it if the red triangle is on.

    Do I need to fix the car where it sits/have it towed, or is it safe to drive home?
    Could it be these codes that made the red triangle light come on, or is there definitely a bigger issue?
    What should my next steps be?

    Any and all advice is appreciated. Thanks in advance!
     
    #1 Eric Seres, Jan 6, 2025 at 5:07 PM
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    Vehicle:
    2006 Prius
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    Four
    Hello, and welcome to PriusChat!

    Is it just the check engine and RToD lights, or are there any others on?

    The two codes you have are both for the Coolant Heat Storage system (set by the ECM - engine control module) It's a "thermos" tank that keeps 2-3 quarts of coolant hot for a few days.

    When you start the car on a cold morning, the hot coolant is pumped into the engine to help it warm up faster. Problems here have no affect on how the car drives.

    This has nothing to do with the "master warning light" (RToD). Most times, this warning appears when there are faults with the hybrid drive system. There can be other things (like low engine oil pressure) that can turn it on, but usually there are trouble codes in the hybrid control or High Voltage battery ecu's.

    I expect your scantool is not capable of checking all 14-16 systems on a Gen2 Prius. Here is a thread that reviews several apps and devices for smartphone. Post 37 is a summary. (I prefer the Autel AP200 for general diagnostics).

    Being there are dozens of possible faults, I can't say whether it's ok to drive or not.

    https://priuschat.com/index.php?posts/3246758

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, Jan 6, 2025 at 11:58 PM
    Brian1954 likes this.
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