Prius 2008, Engine only starts with OBD plugged in

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Prisusi, Aug 20, 2022.

  1. Prisusi

    Prisusi New Member

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    So, we just had some work done on engine, don't know much about prius and cars in general (it's my dad's car). We also changed 12v battery.

    The car turns on normally even without obd plugged in but the engine wont start. There is a red triangle of death (along with other warnings) and red car icon with exclamation on the screen.

    When we plug in the OBD diagnostic tool the engine starts just fine and car moves normally, warnings are still there but they disappear sometimes.

    One more problem that has appeared is low MPG, it averages out to ~25 when it used to be around 50. Any clues? Thanks in advance
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Yeah that's really strange but I don't know if you've got weird OBD2 scanner or something's wrong with the scanner maybe some of the pins are messed up or something like that but the car shouldn't do much different with something plugged into the OBD2 port other than be sending data out that port to some device but making the car not run and all that seems like there's something internal and what's plugged into the OBD2 port that is shorting or crossing something out is there anyone you can like go to advance Auto or whatever they are out in your area and have them scan it with their $20,000 scanner and see if the car does the same thing I guess that would be a good answer or even a cheap Innova scanner just see if you pick up codes and ABS codes and if the car starts or does anything differently I got real trouble with that I mean how are you going to short out your OBD2 plug from the car back I mean it almost seems crazy.
     
  3. bisco

    bisco cookie crumbler

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    get the invoice and find out what work was done on the engine.

    what diag tool? can it read the trouble codes?

    for how long/miles have the mpg been low?
     
  4. Tombukt2

    Tombukt2 Senior Member

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    Yeah that is really low mileage you said what 35 when I was running ice engine only HV battery completely dead Even driving 50 60 mi at a time I was still getting 40 miles to the gallon and when the car is completely fixed and running properly I'm getting about 47 47.5
     
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