Symptoms of failed Mass Air Flow sensor on 2009 Prius...?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jabog6, Jan 22, 2013.

  1. Jabog6

    Jabog6 Junior Member

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    Hello folks,

    I had to have my 2009 Prius towed 2 days ago. It has just over 73000 miles. I was on the highway and suddenly experienced a lack of power. Eventually, the dashboard lit up: check engine light, big red exclamation point, and my favourite: it said "problem" on the center display. I pulled over and let it sit for a few minutes and tried starting it. All the same warning lights came on. The battery level was at 1 bar. The gasoline engine would start for maybe 10 seconds and shut off. I could move the car on battery power only, but I had several miles to go before the next exit, uphill, so I figured I needed to be towed.

    Long story short, my dealer said all this is due to a failed mass air flow sensor, and is charging me $400 to replace it. Does that make sense? I thought a faulty sensor might make the car run roughly or whatever, but not actually prevent the engine from running. Does anyone have experience with this kind of thing?

    Any insight would be appreciated.
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It is reasonable that a problem with the MAF sensor will cause driveability symptoms. You might ask for the tech to try cleaning the original sensor first, rather than replacing it.

    Also, check the engine air filter, the dirty side is on the bottom. It should be replaced at 30K mile intervals.
     
  3. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    $400 to replace the MAF sensor is malarky.

    The part can be bought for $50 at Rockauto and removing/installing it is so easy a caveman could do it!!
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The Toyota dealer is not going to buy parts from Rockauto.

    MSRP of the correct Toyota part is $183, so a $400 dealer repair invoice is not impossible to comprehend.
    2005 TOYOTA PRIUS Parts - Champion ToyotaWorld

    I'm assuming that if the OP had the knowledge to replace the mass air flow sensor, he would not bother to post the query.

    It is true though, that replacing that part will take around 5 minutes. The trick of course, is to know which part to replace and be able to remove the wiring harness connector, without causing more harm than good.
     
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  5. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Haha, yes of course they wouldnt. :D

    Guess I let my DIY mindset get the best of me. I personally wouldnt pay $400 for the Toyota Dealer to replace the MAF sensor, even if it were Jesus himself behind the wrenchset.

    So the Dealer would charge $217 in labor for the MAF sensor replacement? Although the price of the MAF itself ($183) alone makes me fall out of my office chair, that labor is even more extravagant to those of us here who have removed the MAF sensor before to clean it (3 minute job).
     
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  6. Jabog6

    Jabog6 Junior Member

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    Thanks all for your input. I really appreciate your help.

    Not to get us on topic again ;)... but can a MAF failure cause the gasoline engine to refuse to run?
     
  7. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Yes. I searched the site and found a few instances of it.
    Can debris in the mass airflow sensor shut the car down? | PriusChat

    The MAF can go bad or start complaining from bad air filtration, or not be bad but just dirty (I cleaned mine last month & at 60k miles it was dirty), it can also fail from somebody overfilling the engine oil level. The Prius is very sensitive to overfilling and oil will contaminate the MAF wires if that was the case. Some oil change places assume the Prius takes 5 quarts of oil when in fact it only takes 3.9 quarts, but is happiest at 3.5 quarts.

    The more you know.....lol
     
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  8. Jabog6

    Jabog6 Junior Member

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    PriusGuy, thanks for that link. The engine air filter was last replaced less than a year ago, and was clean. I'll keep an eye on engine oil levels. I definitely fill to the higher line on the dipstick, but never over. I'll aim for halfway between the two lines from now on.
     
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  9. wb9tyj

    wb9tyj 2017 Prius Prime Advanced

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    Had the MAF go bad 1 day after i had the 2 recalls done on the prius...i thought at first the recalls had something to do with it, but it was all coincidental...anyway...2 screws later the old one was off and a new one was put on...i did it in about 10 minutes in my garage...given the car would not stay running...frankly it gave us a 2 minute warning...check engine light, then the triangle of death...i pulled the +12V and reset everything...car mileage went from 42 to 48, even with crappy winter blend gas...runs like new...
     
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  10. Avi's Advanced Automotive

    Avi's Advanced Automotive Independent hybrid repair shop

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    Did you try cleaning the old sensor? It is common for debris to get into the MAF and cause a problem, however, These MAF sensors almost never go bad. The air filter could have been inspected while the recalls were being performed causing debris to get into the MAF.
     
  11. wb9tyj

    wb9tyj 2017 Prius Prime Advanced

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    we cleaned the old one with MAF cleaner..and it was very dirty...reinstalled it and was able to get the car running ,however, given that we are out in the middle of the night and in the middle of nowhere 90% of the time...i just did a quick replacement...( at 90,000 miles)...held on to the old one and put it in plastic bag in the tool box just in case...looks like the air filters were alledgedly inspected which could have put some minute debris in there but we cleaned it all up ...of course the oil level was just a tad under full...where it belongs...
     
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  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The next question you might consider is: why was the old MAF sensor so dirty? How often do you change the engine air filter and do you use the correct Toyota filter; or some aftermarket substitute or even worse, an oiled K&N filter?
     
  13. wb9tyj

    wb9tyj 2017 Prius Prime Advanced

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    engine filter every 8-10k miles with oem paper filter...never an oiled filter...and the oil level is always just under full...been changing oil in prii since 04 myself...never could trust dealer ...other than that i guess after 90000miles it just said (MAF) enough...ok changed out and back to normal...
     
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