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Mass Air Flow Sensor Code Will Not Clear
05-09-2014, 09:27 PM
Post: #1
Mass Air Flow Sensor Code Will Not Clear
Hi all. I recently bought a 2001 VW Beetle 2.0. and live in the Washington DC area. When I 1st bought it, I popped a few codes i dont remember, but they were MAF related. I installed a new MAF and all codes went away, but a new one appeared, the dreaded P0103 that was not there before. No matter what i do, it wont go away and i cant pass inspection. here is what ive done.

replaced connector housing
replaced sensor
checked all hoses...no visible or audible leaks.
read voltage and resistance ...heres the results, with all readings taken on the HARNESS side. The last reading of pin 5 is with the MAF connected and the wire was probed.

PIN 2 to ground w/ MAF disconnected...12 VDC
PIN 3 to ground w/ MAF disconnected...12 VDC
PIN 4 to ground w/ MAF disconnected...5 VDC
PIN 5 to ground W/ MAF CONNECTED... 12VDC NO FLUCTUATION

I am lead to understand that the voltage should be fluctuating on PIN 5 as i increase RPMs...it didnt...It just read a constant 12VDC...does this mean Im that lucky guy that bought a crap sensor? It is a Bosch OEM by the way.

Thanks for any input!!
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05-09-2014, 11:10 PM (This post was last modified: 05-09-2014 11:11 PM by Rupe.)
Post: #2
RE: Mass Air Flow Sensor Code Will Not Clear
MAF codes are a funny breed. Many times it's not the MAF but a failure of the MAF numbers to match what the computer (ECM) thinks they should be. IOW, exhaust restriction (clogged cat) or maybe a waste gate issue or diverter valve in the case of a turbo engine. Sometimes it's a vac leak or a boost leak. I am also hearing you may need specialized scan tools just for VW to sort this out. (per a quick look at a few VW forums) Not being familiar with the typical diagnosis of this car I would put the pin checks on the back burner till you sort out the easier stuff. Also consider that the MAP sensor may be throwing a curve ball into the works because that's what reports manifold vac / boost. If the vac hose to that is problematic everything else will be screwed up. Again, hearing some of this may need VW specific scan tools. Personally I lost track of the bug when they took the air cooled engine out of the rear of the car. After that it was a Rabbit or a Golf depending on how you look at it!
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