Motronic 2.7 RPM sensor code (1121) | FerrariChat
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Motronic 2.7 RPM sensor code (1121)

Discussion in '456/550/575' started by rviani, Dec 19, 2017.

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  1. rviani

    rviani Karting

    Jun 22, 2005
    81
    NJ
    Full Name:
    Ron Viani
    #1 rviani, Dec 19, 2017
    I am continuing to get intermittent CEL indications on the cly 1 - 6 side of my 1995 456 gt including a 1121 code that appears along with either a 1211 and / or a 1212 code. Changing O2 sensors side to side results in problem staying on the 1 - 6 side. I am continuing to look at possible causes for the lambda regulation codes but I read on here that a 1121 code will always appear if you check with the engine stopped - although the shop manual does not mention this. my questions are:

    Is it possible to pull codes with the engine running - the shop manual does not mention this?

    Is it true the 1121 code will always appear if codes are pulled with the engine stopped?

    Any help appreciated
     
  2. Red Sled

    Red Sled Formula Junior

    Jan 1, 2013
    618
    Oxfordshire, England
    #2 Red Sled, Dec 20, 2017
    I don't know the 456 but there is a good chance that the M2.7 codes are the same as for the 512TR which I have had this issue with before.
    The short answer to your first question is yes, and in my experience, 1121 can be a red herring, and many just ignore it. The 1211 is MAF/O2/coolant sensors and so you may want to check all of those as opposed to just the O2.

    My 512TR still throws out 1121 but runs fine with no issues/lights etc.

    Worth looking at the 512TR thread here:
    https://www.ferrarichat.com/forum/threads/looking-for-some-help-with-pesky-cels-1211-code.554487/

    and the ECU codes section in

    http://www.my348.com/348.html

    good luck.
     
  3. uberlink

    uberlink Formula Junior

    Apr 23, 2012
    777
    Twin Cities, MN
    Full Name:
    Mark Johnson
    #3 uberlink, Dec 21, 2017
    Join the club. Mine throws that code periodically with no discernable symptoms other than the code. I seem to have noticed that cleaning all the electrical contacts under the hood from time to time minimizes how often it shows up. Might be a placebo, though.
     
  4. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    39,043
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    #4 tazandjan, Dec 21, 2017
    Odds are that an SRI gold connector kit would cure that, but expensive at around $2.5K.
     
  5. Red Sled

    Red Sled Formula Junior

    Jan 1, 2013
    618
    Oxfordshire, England
    #5 Red Sled, Dec 30, 2017
    I find that resetting the ECU by isolating the battery or removing the unit etc leads to fewer 1121 for a period of time. Probably related to ECU re-learning after the power down.
     
  6. rviani

    rviani Karting

    Jun 22, 2005
    81
    NJ
    Full Name:
    Ron Viani
    #6 rviani, Jan 1, 2018
    Thanks all for the input. Once the temperature in my garage rises to something more bearable I plan on further investigation and will post the results.
     
  7. rviani

    rviani Karting

    Jun 22, 2005
    81
    NJ
    Full Name:
    Ron Viani
    #7 rviani, Jan 4, 2018
    Turns out the answers to my questions are:

    1) Yes the fault codes can be accessed with the engine running - although the shop manual does not mention it.
    2) the RPM sensor code will apparently always appear with the engine stopped (how does this make sense??) but not with the engine running.

    Still chasing the lambda codes. Anyone have a good way to read the output of the coolant temperature sensors without removing the intake manifold?
     
  8. johnk...

    johnk... F1 World Champ
    Owner

    Jun 11, 2004
    11,166
    CT
    Full Name:
    John Kreskovsky
    #8 johnk..., Jan 4, 2018
    The RPM sensor is a passive device. It only generates a signal to the ECU when the tooth wheel on the crank is rotating (engine running or cranking). Thus the ECU displays a code when it does not see the signal. Unlike other codes, the 1121 code is not stored in the ECU. It is simple displayed if there is no signal from the sensor. Thus meaningful only when the engine is running or cranking. A car with only 1 RPM sensor won't start/run if the sensor is bad. A car with one for each bank, like a 2.7 setup would only run on one back is one sensor is bad.
     
  9. Red Sled

    Red Sled Formula Junior

    Jan 1, 2013
    618
    Oxfordshire, England
    #9 Red Sled, Jan 5, 2018

    Very useful to know re the 1121 code not being stored.
     

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