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-   -   Help! (http://forum.e46fanatics.com/showthread.php?t=901306)

TheKidRichReg 02-03-2012 06:04 PM

Hey guys, I've had my 2001 330xi (85K miles) for a couple months now and recently noticed poor performance including rough idle and a few stalls when I came to a full stop. After a few more stalls the SES light finally illuminated. I scanned the fault codes and these three came up: P0103, P0172, P0175. I'm going to inspect the intake tubes for cracks tomorrow when it's bright out but I'm sure it's the MAF sensor gone bad. Any suggestions?

White_Knuckles 02-05-2012 03:24 PM

Hmmm, not a bad idea inspecting your boots but a torn boot usually throws lean codes. The MAF is a mysterious device. CRC makes a MAF cleaner spray that may remove contamination on the delicate MAF film or wire. You may have spotted that a Hyundai replacement MAF is out there at much less cost and is a direct cross. My advise is to monitor the codes and not assume anything. Many throw parts at codes and end up chasing their tail. Codes often point to a condition and/or part that is from the affect of something else not the part itself. Example - O2 lean. You swap the sensor only to find it continues to throw O2 lean due to upstream air leaks. Don't assume you've got it nailed by code interpretation alone. Try operating the car with the MAF connector disconnected. It will throw a MAF code and often auto-transmission alert. Not sure what's up with the tranny alert but I've duplicated it and it freaks you out when greeted with the amber trans symbol. Removing the connector will force the ECU into "open circuit" which allows a pre-set factory fuel mapping program to operate. What changed? Did the car run or idle better? Under this condition did other codes appear? You of course need a code reader with reset capability. A basic auto store ODBII reader will work fine for this.

Wayne's World 02-05-2012 03:48 PM

Symptoms sound like a sticking idle control valve. Let it soak in some carb cleaner then blow it out.

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TheKidRichReg 02-07-2012 02:37 PM

I do have an OBDII reader, that's how I diagnosed the problem and cleared the codes. I actually did everything you stated prior to posting here because of info I gathered on other threads. Everything you said, White Knuckles, happened. After disconnecting the MAF sensor, I started the car. The RPM's increased slightly over 1,000, I usually idle around 600. The transmission malfunction (exclamation point in gear icon) light came on, is this the auto-transmission alert you're speaking of? I took the car around for a spin and the same codes came back again.

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