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1999 Isuzu Trooper Question: Codes P0174 and P0300

 

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ksab, 3.5L V6, Brownsville, PA, January 19, 2012, 16:17
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 Rookie

Can both these codes be caused by the mass air flow sensor

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  • Answer #1

    gmc4me January 19, 2012, 17:23
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     Journeyman

    Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is generally the side of the engine that doesn't have cylinder #1.
    Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.
    Possible causes:
    •The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
    •There could be a vacuum leak downstream of the MAF sensor.
    As for the p0300 you may have a diffrent problem. This code is for a random misfire and is not cylinder specific. The cause of your other code may be causing this problem. Fix the p0174 first if doing this on your own then approach the other problem if the p0300 still exist after fix.

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    ksab, January 19, 2012, 18:31
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    Thanks, no vacuum leaks,cleaned mass air flow,replaced throtle position,map sensors and EGR valve.

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  • Answer #2

    mastertech6371 January 19, 2012, 18:11
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     Master

    not likely. you have a vacuum leak on bank 2 for 174. the missfires are most likely plugs, coil or the same vacuum leak.

    Roy

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    ksab, January 19, 2012, 18:28
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    Thanks,but i just replaced all the plug and had one coil pack bad.Engine idles fast . have changed throtle,map sebnsor and egr valve.all coil packs are firing.

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    mastertech6371, January 19, 2012, 19:06
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     Master

    how did you check the coils?? a lot more to checking them than just looking for spark. do not discount the possibility of another coil failure.

    Roy

    The coils are best checked by a scope from a shop. they can verify output and see any failures. not as simple as it sounds.

    Roy

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    ksab, January 20, 2012, 05:01
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    how do you check another way and is there a different coil pack for no. 6 cylinder.

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