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Ed83
Ed83 1/12/2012
1997 BMW 318ti Base 4Cyl1.9L - Engine
code p1174 i replaced a front O2 sensor code come back, also i hv code p1143 air injection sistem
engine light turn after drive for about 120miles
1 Answer
  • Spoon Sports
    Spoon Sports 2/6/2012
    p1174

    Could be probably 1 of 3 things. O2 sensor, vacuum leaks, or mass air meter. First things first, check for a vacuum leak. It means that the MAF is giving the ECU an inaccurate reading and your car is running lean or rich. More than likely it's the ribbed rubber flex boot between the MAF and the ASC valve or throttle body. Take it off and check for splits or cracks. You might not be able to see them from the outside of the boot, sometimes the cracks are hidden between the folds. As a temp fix, you could patch the boot with RTV or epoxy, but make certain that it dries and there's no chance of it flaking off and getting sucked into your engine. Basically, the MAF tells the ECU how much air the engine is getting. In turn, the ECU calculates the air fuel ratio and holds the fuel injectors open for a prescribed interval(pulse). If the reading that the MAF is sending the ECU varies by even the slightest amount, you'll throw a CEL for code P1174(manufactuer controlled air fuel metering). I had the same issue about a year ago and fixed it. The code hasn't came back since.

    BTW, you might also want to clean your MAF. They sell a special cleaner at your local autoparts store. It's made by CRC and it's called MAF Sensor Cleaner. The only safe alternative is isobutol alcohol on a Qtip. Be very gentle and careful not to damage the film inside of the sensor. DONT USE ANY OTHER CHEMICALS TO CLEAN THE MAF

    P1143

    Once you get the P1174 fixed, tell me if the P1143 comes back because these 2 codes are somehow rel;ated.

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