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Secondary Air Injector

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Michael Locatelli, Oct 1, 2017.

  1. Michael Locatelli

    Michael Locatelli New Member

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    I've got an 05 with 210k miles. Changed jobs a year ago and probably only drive 100 miles a month now, if that. Yesterday, got in the car and started backing out when the master warning and check engine lights came on. Got a code reader and plugged it into the OBD-II port and it came up with code P0491 Secondary Air Injection System (Bank 1). I haven't been able to verify that this code has this meaning for the Prius (online search only shows this for non-Prius vehicles and it's not listed in my Haynes manual). On top of that, the Haynes manual makes no mention of this system in the exhaust or emissions systems.

    My question is, can anyone confirm that this code is valid and is indicating an issue with the secondary air injector? If so, any diagrams pointing out the locations of the components of this system so I can start troubleshooting? I'm hoping it's just a hose or relay that needs to be replaced. Thanks for any guidance. I'm going to see if I can trace it back from the head of the exhaust system later today.
     
    #1 Michael Locatelli, Oct 1, 2017
  2. Raytheeagle

    Raytheeagle Senior Member

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    Welcome to Prius Chat (y).

    What OBD reader did you buy? Did you have other issues with your Prius prior to this incident? Did the car run the same after the lights on the dash were displayed?

    Keep us posted (y).
     
    #2 Raytheeagle, Oct 1, 2017
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  3. Michael Locatelli

    Michael Locatelli New Member

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    I borrowed my dad's Innova 3100 reader. No issues with the car in the last 4 years or so. Engine sounds fine but I haven't driven it since the lights came up. Now that I have some information from the code reader, I'm not worried about driving it, but I stole my wife's car to take the kid to soccer yesterday :D. Glad I passed smog a couple of months ago.
     
    #3 Michael Locatelli, Oct 1, 2017
  4. Michael Locatelli

    Michael Locatelli New Member

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    I decided to try clearing the code and driving around a bit before trying to do anything. That cleared up the master warning and check engine lights. Didn't come back up while driving. Looks like this might be one of those things it needs multiple trips to reassess, so I'll have to keep an eye on it the next couple of times I'm driving it.
     
    #4 Michael Locatelli, Oct 1, 2017
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  5. edthefox5

    edthefox5 Senior Member

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    That s air flow to cylinder 1.
    Time to start working on the car. Clean the throttle body and pull the sparkplugs. Cylinder one is unhappy. How much oil does the engine use between oil changes?
     
    #5 edthefox5, Oct 1, 2017
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  6. Michael Locatelli

    Michael Locatelli New Member

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    If it recurs, I'll check that out. I am a bit concerned about oil usage as I usually have to add a quart between oil changes. There aren't any leaks.
     
    #6 Michael Locatelli, Oct 1, 2017
  7. edthefox5

    edthefox5 Senior Member

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    Did the oil level ever get so low it turned on a dash board light to alert you to that?
     
    #7 edthefox5, Oct 2, 2017
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    2G does not have air injection for emissions control, hence the DTC is not valid. Keep your 12V battery fully charged since you hardly drive the car.
     
    #8 Patrick Wong, Oct 2, 2017
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  9. Michael Locatelli

    Michael Locatelli New Member

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    Only when I'm applying the brakes, going down hill and making a turn (I forget if it was right or left, but it's only one of those). Usually happens about 200 miles before scheduled 5k service.

    That would explain why it's not in the manual LOL. My dad said that he was getting that code on his BMW so maybe it got stored in the reader somehow.
     
    #9 Michael Locatelli, Oct 4, 2017
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Do NOT allow the engine oil level to get that low, unless you really want the engine to blow up on you. Check the engine oil level using the dipstick, periodically. Spend $4 on a quart of engine oil and keep the engine oil level near the top dimple of the dipstick, since you know the engine consumes some oil.

    Now that you aren't driving the car that much, you should change the oil at least annually (even if 5K miles haven't been logged since the last oil change.) The purpose of the annual change is to get accumulated water condensation out of the crankcase.
     
    #10 Patrick Wong, Oct 4, 2017
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  11. edthefox5

    edthefox5 Senior Member

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    Yep it's now an oil eater. You let the oil go so low it's destroyed the oil rings on the pistons. Every time you let the pump go dry it makes it worse. So your driving around with no oil in the engine.
    The engine Pistons and connecting rods are splash lubricated . Low oil no splash=engine damage.

    The fact that you see that dashlight and don't pull over and open the hood and check under the hood blows my mind. I assume you get the oil changed at the dealer?
     
    #11 edthefox5, Oct 4, 2017
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  12. Michael Locatelli

    Michael Locatelli New Member

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    Very true. Only excuse I have is that the light clears a second later and doesn't come back. Poor excuse, I know.
     
    #12 Michael Locatelli, Oct 4, 2017
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  13. edthefox5

    edthefox5 Senior Member

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    The Prius is really so reliable most people never open the hoods ever. But that oil eating will really get you as its an ever changing thing and its progress of oil eating quantity has to be monitored as it may suddenly accelerate and your looking at a new engine where you may have been able to just keep it topped off and drive it for a long long time.
    Its just like a human it needs more inspection then when it was young.

    My recommendation is closely monitor it and see how bad it is. Check the oil first thing in the am before you start the car that will give you 100% true reading of oil level as all the oil from the top of the motor will have dripped back to the pan. Seer how bad it is check it every couple of days and write it down.
     
    #13 edthefox5, Oct 4, 2017
  14. edthefox5

    edthefox5 Senior Member

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    Its starts as oil eating then progresses to mild knocking upon load (blown piston bearings) which knock sensor sees and pulls timing so car must be driven very hard to meet past power expectations and that usually progresses to #3 piston through the block. Its always #3 not sure why.
     
    #14 edthefox5, Oct 4, 2017
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  15. fotomoto

    fotomoto Senior Member

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    I'm afraid a much bigger issue is in your future.
     
    #15 fotomoto, Oct 4, 2017
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    You really should get a smart charger, maybe wire up a quick connect for convenience, and just leave the charger hooked up, all the time the car's idle. This is assuming you've got a garage, power.
     
    #16 Mendel Leisk, Oct 4, 2017
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