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  1. #1
    Join Date
    Aug 2016
    Location
    Steamboat, CO
    Posts
    7

    Default Help with High idle issue and CEL codes

    Hey guys! This is my first XC70 that I've owned but my third volvo so far. I just had the CEL come on for the first time the other day. I have a VIDA reader and I got codes:

    ECM-120C Air mass signal -- too high (P0100 OBD code)
    ECM-951C Engine control module (ECM), idle control -- Signal too high (P0507 OBD code)

    symptoms are a high idle in park and neutral (obviously) and it just started randomly with nothing clear to cause it that I recall

    Any ideas what's causing these two codes? Is my MAF shot already? I just cleaned it with MAF cleaner last night to see if it would change anything to no avail. I also noticed while trying to check for vacuum leaks and whatnot that my upper PCV hose/pipe is cracked in a few places. New hose on the way for that. Is my whole PCV system shot and causing the problems?

    Any help is appreciated! Thank you!

  2. #2
    Join Date
    Aug 2016
    Location
    Steamboat, CO
    Posts
    7

    Default

    Here's a pic for visual aesthetics

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  3. #3
    Join Date
    Dec 2009
    Location
    GA
    Posts
    1,320

    Default

    Quote Originally Posted by nsfwaldo View Post
    ECM-120C Air mass signal -- too high (P0100 OBD code)
    ECM-951C Engine control module (ECM), idle control -- Signal too high (P0507 OBD code)

    Any ideas what's causing these two codes?
    If you have a copy of Vida - click on fault tracing, then diagnostic trouble codes and associated procedures. Find your codes in the list and try what Vida recommends.

    A dirty throttle could cause an erratic idle, and that is one of the possibilities listed for air mass codes.

  4. #4
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    516

    Default

    What model year and how many miles? If you're over 100k and you want to keep the car for a while, a PCV replacement is probably in your near future. Not to say that this is the cause for your CELs. When the PCV system becomes clogged with oil deposits, you won't necessarily get a code but the blockage will build pressure in the crankcase and blow out your oil seals. This can result in RAPID oil loss!
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  5. #5
    Join Date
    Feb 2010
    Location
    Virginia Beach
    Posts
    3,853

    Default

    Upper PCV hose crack = vacuum leak.

    As was said - do the whole system. The parts don't age well and you're best off to simply replace all of the PCV parts with new ones. Get a kit like the one from IPD. Fixing the vacuum leak will certainly help your idle issues.
    Current Fleet:
    2016 Tundra Crewmax 4WD 1794
    2005 MB S600 (100K, Michelin AS3+, M1 0W40)
    2002 V70-XC (238K, Castrol Edge 0W40)
    2002 V70-T5 (195K, IPD bars, Bilsteins)
    2001 V70-T5 (76K)
    1932 Packard Sedan (straight 8, dual sidemounts, original paint and interior, Shell Rotella 15W40)

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