Prius C Key and Ecu whipped by locksmith

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by 2012PriusCCO, Apr 27, 2026.

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  1. 2012PriusCCO

    2012PriusCCO New Member

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    Hi everyone, I’m looking for advice on a pretty serious issue with my 2012 Toyota Prius c.

    I lost all my keys and had to call a local locksmith. He wasn’t able to program a new key, could get lights to turn on dash and everything, so he called another locksmith to help. After trying, the second guy told me that the first locksmith had somehow deleted all the key information and caused an ECU-related issue. He couldn’t get the lights on dash to light back up

    I ended up having the car towed to a Toyota dealership, and they’ve now had it for two weeks. The head mechanic (who mentioned he’s Toyota-trained ) says it’s about a 9-hour job just to replace/reprogram the immobilizer/key computer and the smart key computer assembly. On top of that, they still need another 2 hours of diagnostics as well as 12 volt battery has gone bad .

    They’re estimating around $3,700 for the repair — and even then, they say there’s no guarantee it will fully resolve the issue.

    Has anyone here experienced something like this? Is it really possible for a locksmith to wipe out the key/ECU data like that? And does this quote sound reasonable, or should I be considering other options (like a second opinion, different shop, or even replacing modules myself)? I’ve called other Toyota dealerships who have the parts for half the price / other dealerships 3 hours away said 3 hours for ecu .

    Any advice would be really appreciated. Thanks!
     
    #1 2012PriusCCO, Apr 27, 2026
  2. 2012PriusCCO

    2012PriusCCO New Member

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    Anyone have any advice
     
    #2 2012PriusCCO, May 10, 2026
  3. BiomedO1

    BiomedO1 Senior Member

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    Sorry to hear that. I don't know if your immobilizer is damaged or just needs to be reflashed/reprogrammed. Unfortunately, the right place for that job. Third party locksmiths are most likely using 3-party tools to mess with the immobilizer and can damage it. The OEMs' doesn't make it easy to crack their immobilizer - otherwise cars could be electronically stolen at an alarming rate (no pun intended). The dealership has OEM electronically registered tools and has the best chance of fixing this.

    Did either independent locksmith hook-up a 12V battery charger or jump pack to the car, while they were messing with the ECU? A low 12V battery would definitely mess up a re-flash. IMHO - I believe that's step 2 or 3 in the OEM diagnostic procedures.

    Hope this helps...
     
    #3 BiomedO1, May 11, 2026
  4. 2012PriusCCO

    2012PriusCCO New Member

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    Toyota did say my 12 v battery was bad and needs to be replaced on top of everything else, prior to this the locksmith did jump my battery. All the lights turned on at first but whatever he did, the lights on dash never turned back on fully
     
    #4 2012PriusCCO, Jun 3, 2026 at 4:31 PM
  5. 2012PriusCCO

    2012PriusCCO New Member

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    And then he left and brought other local locksmith to try before telling me his buddy deleted all key information and that ecu is showing some error code
     
    #5 2012PriusCCO, Jun 3, 2026 at 4:32 PM
  6. 2012PriusCCO

    2012PriusCCO New Member

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    Still waiting to hear from Toyota, they said they need to two more hours of diagnostics
     
    #6 2012PriusCCO, Jun 3, 2026 at 4:33 PM
  7. BiomedO1

    BiomedO1 Senior Member

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    Unfortunately; battery charger/jump pack should be hooked-up and operating FIRST. Power fluctuation will mess-up a reflash/reprogramming.
     
    #7 BiomedO1, Jun 4, 2026 at 12:01 PM
  8. rjparker

    rjparker Tu Humilde Sirviente

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    Replacing an immobilizer ecu is one of the most time consuming procedures because the dash has to come out followed by the heater / ac system just to get to that ecu.

    When all keys are lost it is necessary to clear all programmed keys in the immobilizer ecu using the latest Techstream followed by the programming in a new key procedure. Licensed locksmiths can have a special Techstream version to do this clear.

    So the first locksmith was doing what was required but the process apparently failed during the new key setup. Power interruption is one of the ways it could fail.

    It would seem the ecu is or was still communicating after the initial all key clear, otherwise they would not know that information.

    I have to assume Toyota is desperately trying to make a new key work before requiring a complete dash disassembly which could be $2000 just for labor plus more for a new immobilizer ecu, key and setup.

    While it is water under the bridge, ALWAYS get a second key bought and functional before all keys are lost. it is almost diy easy to add a key when you have one working, certainly not more than $300-$500 at a dealer.

    As a side note, in 2022 during covid, Toyota did not have enough new key fobs to sell with their new cars. So they sold cars with one fob and gave you an iou for the second. I bought a 2022 Rav hybrid with one key and waited a couple of months. I then bought a second key from an online Toyota dealer at a discount (Toyota had some at the distributor level for lost key issues) and had my dealer add it.

    15 minutes while I waited was all it took.

    Moral of the story, always have a second key so that you can afford to lose one. When you get it fixed, be sure you get two keys.
     
    #8 rjparker, Jun 4, 2026 at 12:49 PM
    Last edited: Jun 4, 2026 at 12:58 PM
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