Red Triangle and no codes. Help!

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Raghav, Aug 25, 2025 at 9:32 PM.

  1. Raghav

    Raghav Junior Member

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    My 2006 prius has a reconditioned battery and has been running fine. Recently when I was driving, the red triangle came on (and small red car on the console). No check engine light though. I immediately returned home and switched car off and on. Now triangle and all lights in the dash was on, including check engine light. I used an OBD II scanner (not the bluetooth one, a decent one). However, it did not show read any codes. In frustration, I used clear code option, and triangle and other lights went off.

    I think I should have used the techstream, but didn't occur at that point. I have to wait till the triangle comes back now I guess.

    Now it is driving ok, but I am hesitant to use it normally. I initially thought it may be hybrid battery, but battery seems fine, holding charge and works as it used to, drives quite a distance at low speed on battery without dropping charge rapidly. I checked the oil and coolant. Coolant reservoir was close to empty, but the coolant tank had sufficient fluid. I topped up the coolant reservoir, and got the coolant circulation checked with a mechanic. Oil level is fine.

    Is there anything else that can cause red triangle? How do I troubleshoot?
    I got the front bearing hubs and brakes replaced recently by a local mechanic (he is good at what he does). Could anything have gone wrong with that procedure?

    Thanks in advance!
     
    #1 Raghav, Aug 25, 2025 at 9:32 PM
  2. PriusCamper

    PriusCamper Senior Member

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    Let us know what type of device you're using to read the error codes?

    Also go back to mechanic and ask them to connect these two pins in the OBD2 port together so he can read the blink codes because sometimes no error codes and red triangle mean brake problems that require reading the blink codes.

    upload_2025-8-25_18-45-15.png

    If red triangle comes back before you visit him, then you can:

    1. Short pins 4 and 13 of the OBDII port and then make car Ready.
    2. Press the brake pedal 8 times within 5 seconds.
    3. lights should go off if no problems remain.
     
    #2 PriusCamper, Aug 25, 2025 at 9:45 PM
  3. Brian1954

    Brian1954 Senior Member

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    Odds are that the red triangle will return if you drive the car. Once the triangle returns, use Techstream to check for codes. If you get the P0A80 code, take a picture of the freeze frame data and post it here.

    There are over one hundred different problems that can cause the red triangle to be activated. Begin troubleshooting by getting the trouble codes using Techstream.
     
    #3 Brian1954, Aug 25, 2025 at 10:02 PM
  4. Brian1954

    Brian1954 Senior Member

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    The red triangle comes on when there is a problem with the hybrid drive system in the Prius. The problem could be the inverter, hybrid battery, MG1 or MG2 electrical motors, etc, etc. The trouble codes will give you a clue what the problem is. Techstream will give you the trouble codes so that you can start to fix the problem.
     
    #4 Brian1954, Aug 25, 2025 at 10:10 PM
  5. ChapmanF

    ChapmanF Senior Member

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    Yes, there often will be brake codes at the same time, but as the result of the hybrid system lighting the red triangle, not as the cause.

    The hybrid system and the brake system communicate (because regen braking calls on them to cooperate), so the brake system knows when there are hybrid system trouble codes. The brake system then sets its own codes, C1259 / C1310, which mean "there are hybrid system codes, go look at those".

    If you read the blink codes, C1259 shows up as 58 on the ((!)) light, and C1310 as 51 on the skiddy-car VSC light. Naturally, there's little point trying to clear those as brake codes. Given that they mean "there are hybrid system codes", they'll go away when those are dealt with.
     
    #5 ChapmanF, Aug 25, 2025 at 10:21 PM
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