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Car went to limp mode then stopped with P0A0F after maintenance

Discussion in 'Gen 2 Prius Technical Discussion' started by EboMike, Oct 19, 2013.

  1. EboMike

    EboMike New Member

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    I have a 2005 Prius. After driving home from a 95K routine maintenance inspection, the car (with the display indicating 50% in the gas tank) went to limp mode and then stopped entirely and had to be towed back to the dealer.

    The codes pulled were
    P0A0F (Engine failed to start)
    P3000 (Battery control system)
    B2799 (Immobilizer Malfunction)
    P3190 (Poor engine power).

    The techs concluded that the car was simply out of gas and the display incorrectly showed I still had gas in the tank due to a broken sender in the tank. They also said they added 1 1/2 gallons, and the car ran fine again.

    However, I keep meticulous records of when I get gas, and according to my numbers I had at least 5 gallons left in the tank. Sure enough, the tech topped the tank up, which only took 4 gallons, so clearly my tank was not empty when this happened.

    Now we're all dumbfounded. The dealer still recommends replacing the gas tank for $1000 or so, but the initial diagnosis of an empty tank is incorrect, so I don't buy it. What could have caused the car to stop? Everything is fine now, no warning lights on, but I figure this may happen again.
     
    #1 EboMike, Oct 19, 2013
  2. Mr.Electric

    Mr.Electric Member

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    Leaves and other junk from the air filter falling on the mass airflow sensor after service can cause that scenario.
     
    #2 Mr.Electric, Oct 19, 2013
  3. ursle

    ursle Gas miser

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    The 95k inspection is possibly problematic, often, just hooking up the scangauge after having it in another vehicle sets off my dashboard lights, had a highlander hybrid, the two times it went to the dealer it had to be jumped to restart after turning it off.(both in parking lot's far away)

    Definitely another dealers opinion is in order.
     
    #3 ursle, Oct 19, 2013
  4. ccdisce

    ccdisce Active Member

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    If the CAN Bus gets 'glitched' by a 'defective' third party device being connected to it, the protocol will be for all the computers ( around 7 devices including the gas tank's) to 'BUS OFF' for a while and then retest and re-connect to the CAN Bus if it checks out OK.
    The DTC last cleared distance is probably set to zero by now so you may have to drive for some distance (probably around 350 miles) for the system to be declared sane.
     
    #4 ccdisce, Oct 19, 2013
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    If the problem happens again, then one reasonable possibility is that the fuel pump has an intermittent failure, and it would be necessary to replace the entire fuel tank since the fuel pump is housed within. This is why your dealer suggested replacing the fuel tank.
     
    #5 Patrick Wong, Oct 19, 2013
  6. EboMike

    EboMike New Member

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    Thanks everybody for the replies! In researching this, I found another thread on priuschat that dealt with similar error codes popping up. In that case, several people suggested the engine oil has been overfilled.

    Makes sense since this was a 95K - at the same time, this was at a dealership, not some shady Jiffy Lube kind of deal, so I would expect them to go by the book and know the proper amounts inside out.

    Is there any merit to overfilling in this case?
     
    #6 EboMike, Oct 20, 2013
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    You are the only one who can determine whether the engine oil level is too high.

    If the level is substantially high, like one quart overfilled or more, then yes, it is possible that would cause an engine no-start situation.
     
    #7 Patrick Wong, Oct 20, 2013
  8. Mr.Electric

    Mr.Electric Member

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    The gen 2 is know to get no start from
    over filled oil. The Atkins cycle motor pushes oil up the intake onto the mass air flow sensor and it stops reading air flow. No air flow = no gas from injectors.
    Two frequent no starts after basic services :
    - leaf matter dumped off air filter into intake covers maf
    - oil over fill coats maf after some miles.
     
    #8 Mr.Electric, Oct 20, 2013
    uart likes this.
  9. uart

    uart Senior Member

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    Ok I was thinking this was like a road worthy inspection or something, not an oil change. However now I see it was actually an oil change then yes, an overfill would be my first guess. Check it and see if it's overfilled. If so it was probably even higher straight after the oil change as it tends to burn off the overfill fairly quickly (while fouling the intake system in the process).

    Personally I think it's a good idea to always check the oil level for yourself after anyone else has touched it!
     
    #9 uart, Oct 21, 2013
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