1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Red Triangle and Codes P0A0F, P0121 (Still Operational)

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Billiam229, Jul 29, 2024 at 4:37 PM.

Tags:
  1. Billiam229

    Billiam229 Junior Member

    Joined:
    Oct 9, 2022
    1
    0
    0
    Location:
    San Diego
    Vehicle:
    2009 Prius
    Model:
    II
    Hey There,
    I have a 2009 Prius with 246k and the original hybrid battery.
    I got a the Red Triangle of Death on a drive home earlier this month. The car made it home but there was a loss of power. Scanned it and got
    P0A0F [0x0A0F]
    Hybrid drive system - engine failed to start
    P0121 [0x0121]
    Throttle position (TP) switch A/accelerator pedal position (APP) switch A - range/performance problem
    Accelerator Pedal Position Sensor / Throttle Position Sensor A Range / Performance
    I cleared the codes and drove around the neighborhood. And it was operating normally. Eventually did reproduce the issue, same codes.
    In both cases it was a hot day and I had started the AC some time beforehand.
    Cleaned the MAF sensor but really didn't see any debris or dirt. The inverter pump is running too (I can see turbulence in the fluid container.)
    Since cleaning the MAF sensor, the car is running normally. I've put mileage on it driving around town. But I'm hesitant to do a longer trip especially in the heat.
    Any suggestions to get my confidence back in my ride?
    Thanks,
    Bill
    P.S. There is also a code P0420 related to my catalytic converter:
    Catalytic Converter System Bank 1 Efficiency Below Threshold
    But I've been told the cat needs to be replaced. It's intermittent.
     

    Attached Files:

    #1 Billiam229, Jul 29, 2024 at 4:37 PM
  2. Brian1954

    Brian1954 Active Member

    Joined:
    Jan 31, 2021
    855
    316
    0
    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    You have a problem with the throttle body or the wiring to the throttle body. Check the wiring first. If wiring checks out okay, them look at replacing the throttle body with a used one.
     
    #2 Brian1954, Jul 30, 2024 at 9:54 PM
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    24,150
    15,724
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The one-liner "fortune cookies" for those throttle and pedal sensor codes can be confusing, because the throttle sensor and pedal sensor are completely different items but their trouble codes all share the "throttle / pedal position sensor / switch" wording.

    Brian1954 has given the right call, P0121 (sensor "A") is about the throttle and not about the pedal.

    There's more about those sensors (and why the codes are the way they are) in this post.
     
    #3 ChapmanF, Jul 30, 2024 at 10:29 PM
(You must log in or sign up to post here.)