p0172 and p0175 running rich

Discussion in 'LR4' started by woodruft, May 16, 2018.

  1. woodruft

    woodruft New Member

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    Guys,

    I have 2012 LR4 5.0 that I just got two fresh codes on. According to my OBDII reader, these are the codes. I have seen this on the LR3's but I have not found any information on this on the 5.0's. The car is runs fine with no misses in the engine or rough idle. I have read where O2 sensor could be faulty or the MAF sensor is dirty? Any advice on where to start?

    Thanks!
     
  2. jlach993

    jlach993 Active Member

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    I had the same exact issue with my LR4 back when it had 70k miles. I removed both MAF sensors and cleaned them with MAF cleaner. At around 71k miles the codes came back. I cleaned again and it was all good again until 73k miles. Then it occurred to me that around 68k miles i dropped 2 K&N air filters in the truck. Those filters are oiled filters. They coat em in oil unlike the regular paper filters. It turns out the oil from the filter were being sucked into the engine and coating the MAF sensors. If you don't have a K&N filter then just swap out your air filter with a paper one preferably the MANN one and clean your MAF sensors out. If the codes come back then you need two new MAF sensors.
     
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  3. afour_98

    afour_98 Member

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    This just started happening to my 2010 LR4 with 187k miles on it. I've checked the air filters (clean, no oil) and cleaned the MAFs, but the codes come back in a day or two. Do you really think I need two MAFs (would they both go bad at the same time?). Could it be O2 sensors? or something else?
     
  4. jlach993

    jlach993 Active Member

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    Well it's a good bet that it's one of the MAF sensors. One bad one would trigger the codes. Just replace both with OEM ones since you can't pinpoint which one is the bad one. If not then you have an oxygen sensor issue, but my bet is the MAF sensor. It's the cheapest thing you could replace first anyways. It could also be the MAP sensor as well.
     
  5. woodruft

    woodruft New Member

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    Well I did a couple of things to eliminate the issue. I cleaned both MAF sensors with "MAF cleaner". They both looked like new when I removed them but I cleaned them anyway. Both paper air filters also looked like new, no dirt at all. I had my wife fill up the next day with high test and I added a bottle of STP injector cleaner. Then cleared both codes with my OBD II scanner. 9 days later the codes have not showed back up. Im thinking about changing the spark plugs but want to wait and see if this helps. The Short term and long term trims are all reading below 10%. I cant really tell what tripped the codes in the first place. I will keep an eye on this and post back if anything changes.

    p0172 and 175 suggest that both banks are reading rich so its hard to imagine that an O2 sensor is going out. If one bank was high I could see that. MAF seem to be my number 1 suspect but who knows. Maybe bad gas or I had an injector/s acting funny. Still a mystery at this point.
     

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