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BMW Mass Air Flow Sensor Replacement
 
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Pelican Technical Article:

BMW Mass Air Flow Sensor Replacement

Nick Czerula

Time:

1 hours1 hrs

Tab:

$200

Talent:

**

Tools:

Flathead screwdriver, T20 Torx driver

Applicable Models:

BMW 325i/xi Sedan (2006)
BMW 328i xDrive Sedan (2009-11)
BMW 328i/xi Sedan (2007-11)
BMW 330i/xi Sedan (2006)
BMW 335d/i/xi Sedan (2007-11)
BMW 335i xDrive Sedan (2009-11)

Parts Required:

Mass air flow sensor, engine air filter

Hot Tip:

Work with a cool engine. Clear engine fault codes when done

Performance Gain:

Car will run well.

Complementary Modification:

Replace engine air filter, inspect intake air ducts for cracks.

The mass air flow sensor monitors air flow into the engine and creates a digital signal for the DME. Mass air flow sensors accuracy skews over time and can lead to fault codes or drivability problems. When replacing, inspect the plastic intake air ducts for cracks or dry rot. If intake air ducts are faulty, replace them first and see if the problem you are having is remedied. An un-metered air leak downstream of the mass air flow sensor will set codes similar to a faulty mass air flow sensor. When you suspect a mass air flow sensor as the culprit for setting a fuel trim fault code, check when the fault code was set. You can do this using OBD II freeze frame data. Normally, a vacuum leak would set a fuel trim fault code at idle or very low engine RPMs. A mass air flow meter would usually set a fault code when you are driving, or a higher RPM. You can check your fault code freeze frame data using an OBD II scan tool, similar to how you would check for fault codes.

Turn engine OFF and remove remote key from key slot.

Disconnect mass air flow sensor electrical connector by releasing tab with small flathead screwdriver and pulling connector out of sensor.
Figure 1

Disconnect mass air flow sensor electrical connector by releasing tab with small flathead screwdriver and pulling connector out of sensor. (green arrow)

Remove two T20 Torx fasteners from mass air flow sensor.
Figure 2

Remove two T20 Torx fasteners from mass air flow sensor. (green arrows)

Remove sensor from intake air duct.
Figure 3

Remove sensor from intake air duct.

If stuck, use a small flathead screwdriver to gently pry out of duct.
Figure 4

If stuck, use a small flathead screwdriver to gently pry out of duct. Install new mass air flow sensor into air filter housing. If O-ring gives you a hard time going in, apply a small amount of dish soap to O-ring, it will slide right in and the soap will not damage O-ring. Check vehicle for fault codes, see our tech article on reading and clearing fault codes. Then test drive vehicle and confirm engine runs well.

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Comments and Suggestions:
Colin Comments: hello! i am getting the following codes and issues on my 2007 328xi N52:

rough idle upon cold start
Service Engine Soon/misfire upon wide open throttle
29E1 Mixture ctrl 2
29E0 Mixture ctrl
2D06 Air-mass system
29CF misfire cyl 3 this jumps from cyl 4 to cyl 5 etc etc after clearing fault codes

my local indy told me it was a bad coil and replaced all 6 coils/plugs. aggravated because i don't think it was a bad coil or plug at all.

i recently installed a K&N air filter after letting it dry [they come so heavily oiled!] for a few days.
is there a chance the filter permanently harmed the MAF?
i have taken the MAF sensor out and cleaned with MAF sensor cleaner. it doesn't seem to have helped.

should i smoke test? bad DISA valve? bad MAF sensor?
November 23, 2016
  Followup from the Pelican Staff: Do you still have a misfire?
The K&N is not a good idea, the oil is not good for the MAF sensor.

You will need to check fuel trim to see when it is skewed, idle or part load. Then you will have direction as to what to suspect. - Nick at Pelican Parts
 
THABANG Comments: HI,I AM DRIVING 325i coupe 2009 MODEL,MY PROBLEM IS IDLING WHEN IT IDLE IT LOOKS AS IF IT WANTS TO STOP AND THE REF-COUNT KEEP ON GOING UP AND DOWN AND WHEN I DRIVE IT IT DOESNT HAVE A POWER,THE ENGINE IS EVEN SHAKING.PLEASE HELP
October 20, 2016
  Followup from the Pelican Staff: Is the check engine light on or flashing when the problem is present? Sounds like an engine misfire. I would check spark, fuel and compression on all cylinders.
- Nick at Pelican Parts
 
Calvin Comments: Thanks Nick.
I did check both Valve/Pump. both works. The Service Engine Soon light on when the car park Engine off for more than 12hr, I can smell fume of gas. But engine run good. If engine still warm or hot within 10hrs, the fault light will not turn on because the engine still warm, and the engine running also good. Is that the Mass Air Sensor problem? and also sometime this code 2A87 come on with 2A00. Thanks again for helping us.
September 3, 2016
  Followup from the Pelican Staff: If the valve and pump are good, tjhe ports in the cylinder head may be clogged. With the engine idling, command the pump on, do both front o2 sensors dip and hold lean when the pump is commanded on? - Nick at Pelican Parts  
Calvin Comments: I have a fault code, First Engine-DME Motor Electronics and the code is 2A00 DME Secondary air system on my scan.
My car is 2009 BMW 328I convertible.
Thanks
August 29, 2016
  Followup from the Pelican Staff: Check if the secondary air valve and pump are working. - Nick at Pelican Parts  
Kofi Comments: So I read other postings where some one asked about whether the BMW 335 has a MAF sensor. Your response was the 335 estimates air flow with other sensors . Can you advise which other sensors you referring to? Thanks
August 16, 2016
  Followup from the Pelican Staff: TPS, MAP and RPM. - Nick at Pelican Parts  
Kofi Comments: Guys I need help here. I am losing my mind.
So I have a 2009 BMW 335 Convertible No xDrive. I have a 0172 code and need to replace my MAF sensor. I have looked everywhere I know it should be by the air filter box-Nada! I can't find it. Does anyone know if the 2009 335 does not have or does have a MAF Sensor? If it does kindly point me in the right direction. Thanks
August 16, 2016
  Followup from the Pelican Staff: Your vehicle does not use one. Check for intake air and charge air duct air leaks. - Nick at Pelican Parts  
garicktsui Comments: I owned a 2006 E91 320i before, the MAF is located inside the air box. Nick, you have to remove the whole air box first then release the screws on the bottom of the air box. Then you can see your MAF is inside.
June 28, 2016
  Followup from the Pelican Staff: Ok, we don;t have 320is in the US. Thanks for the info. - Nick at Pelican Parts  
Nick Comments: Hi Nick,

I cnnot seem to locate the MAF Sensor on my E91 -2008 320i M Sport Touring? Any help would be appreciated.
June 7, 2016
  Followup from the Pelican Staff: Your vehicle may not have one. - Nick at Pelican Parts  
John Comments: I saw a guy doing a smoke test with a cigar...just blew smoke into the vacuum system. On a 2006 325i where would be the optimal place to inject smoke?
March 24, 2016
  Followup from the Pelican Staff: That won't work. You need smoke from an inert air pumped system that can seal and raise the system pressure to a psi or two. A smoke machine designed for automotive testing is best. - Nick at Pelican Parts  
Novice Comments: Hi
I have 318D 2010 reg.It had service about 4 months ago in indie garage.
over the last one month Car is playing up-higher fuel usuage/rough idling/momentary lack of power-and i suspect dirty MAF sensor.
But in my car after out MAF sensor cables-I cant see any torx screws.It looks like a solid plastic peice!!
Can you help?
And is there any thing else i would need to rule out?
No warning lights have come up yet.
January 9, 2016
  Followup from the Pelican Staff: I would assume a fuel delivery problem. However, best bet is to check the DME for fault codes before replacing parts. - Nick at Pelican Parts  
Disman Comments: Doe the 335 have one? I don't see it anywhere
July 23, 2015
  Followup from the Pelican Staff: No. 335i models estimate air flow from other sensors. - Nick at Pelican Parts  
Travis Comments: For BMW 328i 2007, getting fault code P1415. The code tripped after reset while at idle sitting in my driveway. The car is running rough at idle, going up and down in rpm and shaking. I am guessing the problem is a vacuum leak, based on note above. Any advice on how to find.
April 13, 2015
  Followup from the Pelican Staff: Vacuum leaks can be found using a smoke machine. Adding smoke to the intake system, looking for escaping smoke. No other safe way to do it. - Nick at Pelican Parts  
Tim Comments: Hi Nick:
What's the normal reading of the MAF? I got 24kg when car startup which I don't think it's normal.
February 22, 2015
  Followup from the Pelican Staff: What vehicle are you working on? When RPM was your reading taken? What elevation are you at? - Nick at Pelican Parts  
Tray Comments: I pulled air cleaner and hose came off of throttle short hose.
I put soap on ends and it took a herculean effort to get the hose lip to lock in place. When I heard it snap it was sealed and I tightened hose. Problem solved, Not bad for a 84 yr youngen

Thanks
July 2, 2014
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
Tray Comments: I had a fault code at idle, I recently had intake manifold removed to replace starter. Had trouble getting hose to throttle tight. I suspect leak at fitting. This article has been a great help.
June 30, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
Let us know what you find. - Nick at Pelican Parts
 

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Page last updated: Sat 12/3/2016 02:23:35 AM