Intermittent P0101

Discussion in 'Mk5 VW Jetta, Sportwagen, and Audi A3 TDI forum' started by terpsgeorgia, May 19, 2017.

  1. terpsgeorgia

    terpsgeorgia New Member

    Joined:
    Nov 26, 2016
    Messages:
    6
    Car:
    06 Jetta TDI
    Location:
    Atlanta
    2006 Jetta. I bought the car from a former Czech Republic Diesel mechanic who has torn all the piping off the front of the car from the airbox forward. I was getting rare but occassional P0101, primarily on long drives when coasting downhill or when close to a semi on the highway. The frequency of the code was increasing so I put a new MAF sensor on, and now it is much more frequent (may put the old one back on). It will come on, I'll clear it, and keep driving and it does not come on again for a while. I imagine if I just left it, it might go off on its own. No other codes, no drivability issues, still 47+ mpg on highway. But it is a nuisance. Any suggestions?

    From some digging on the forum, I read one thread that seemed to associate this with cam lobe wear, so I can go check that out. Also could be wiring I guess...

    Thanks again for any suggestions.
    Larry A
     
  2. terpsgeorgia

    terpsgeorgia New Member

    Joined:
    Nov 26, 2016
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    Car:
    06 Jetta TDI
    Location:
    Atlanta
    Yeah, I know. Read the wiki on MAF and EGRs.
     
  3. terpsgeorgia

    terpsgeorgia New Member

    Joined:
    Nov 26, 2016
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    Car:
    06 Jetta TDI
    Location:
    Atlanta
    So after reading much here, I am coming to the conclusion I need to check my cam lobes. I am guessing I am learning a valuable lesson (and maybe expensive one). The VW Diesel expert from whom I purchased the car said only run 15W40 full synthetic diesel oil with zinc additive. I read on the site to only use 505.01, which I did in the 10,000 miles since I changed the oil. But I missed the provision of - only use 5W40 505.01 oil. Reading the forum more closely now, I see the error of my ways since the 505.01 I purchased was in fact 5W30.. Heavy sigh.

    I am guessing I was probably headed towards this path anyway and this may have just accelerated it.
     
    Last edited: May 22, 2017
  4. Keithuk

    Keithuk Super Moderator

    Joined:
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    6,941
    Car:
    2010 Golf GTD (170) CBBB
    Location:
    Stoke on Trent, England
    That's a common code.

    VAG Error Code: 16485/000257/4794/5667

    EOBD II Error Code: P0101

    Fault Location:
    Mass Air Flow (MAF) Sensor (G70) - Circuit Range/Performance Problem/Implausible Signal

    Possible Cause:
    Malfunction Indicator Lamp (MIL)(K83) active.
    Loss of Power.
    Erratic Idle.

    Wiring/Connector(s).
    Air Leak(s) after Mass Air Flow (MAF) Sensor (G70) .
    Excessive restrictions in the Intake/Exhaust System.
    Dirty air filter, clogged snow screen, clogged CAT.
    Mass Air Flow (MAF) Sensor (G70) faulty,
    Ground Spots corroded or Paint Residue.

    Possible Solutions:
    Check/Replace all faulty Wiring/Connector(s).
    Check Intake Air Filter.
    Check Mass Air Flow (MAF) Sensor (G70).
    Check Earth Points.
    Read Measuring Value Blocks (MVB).
    Mass air flow vs upper threshold model < 60 - 800 kg/h.
    Lower threshold model < 0 - 400 kg/h.
    Load calculation > 18%.
    Fuel system < -17%.

    Special Notes:
    In MY 1995-2002 (?) in Europe at VW diesel cars Mass Air Flow (MAF) Sensor (G70) had the bad reputation of slowly losing his performance, causing loss of power. It's not a matter of defective or breaking down, but it is filthy / dirty (not easy to clean). You can check functionality by making a log in [01-engine], [Measuring Value Blocks (MVB) - 08], group 003 (3e gear, full throttle, from 1700-4000rpm).
    It is not uncommon for a TDI to set Implausible Signal Mass Air Flow Sensor (G70) faults when the engine performance is reduced due to a mechanical problem. These mechanical problems may include, but are not limited to:
    Faulty electric fuel pump or Restricted fuel filter. See the Fuel Pump Basic Settings for PD, PPD, and CR TDI Engines page for Basic Settings tips after replacement.
    Excessive restrictions in the intake/exhaust system.
    Internal camshaft/valve/lifter problems.

    Tech Notes:
    Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor.

    When is the code detected?:
    A high voltage from the sensor is sent to Engine Control Module (ECM) under light load driving condition.
    A low voltage from the sensor is sent to Engine Control Module (ECM).

    Description:
    The Mass Air Flow (MAF) Sensor (G70) is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. It consists of a hot film that is supplied with electric current from the Engine Control Module (ECM).

    The temperature of the hot film is controlled by the Engine Control Module (ECM) a certain amount. The heat generated by the hot film is reduced as the intake air flows around it. The more air, the greater the heat loss. Therefore, the Engine Control Module (ECM) must supply more electric current to maintain the temperature of the hot film as air flow increases. The Engine Control Module (ECM) detects the air flow by means of this current change.

    As taken from my new Free EOBD II Error Codes software
     
  5. terpsgeorgia

    terpsgeorgia New Member

    Joined:
    Nov 26, 2016
    Messages:
    6
    Car:
    06 Jetta TDI
    Location:
    Atlanta
    the edge of my #4 cam lobe is razor sharp. So yeah, I need a new cam.
     

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