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MAF Problem? please help

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Hi, all!

I just learned about this site and I'm very happy that I did.

If it's not too much trouble, I would like to ask for a help.

I have 2003 Boxter S and it seems like I have some problem with MAF but I can't be certain.

Symtoms: Engine stalls easily when I lift foot off of gas pedal. And Idle rpm is unstable. I have PSM and ABS lights on (PSM and ABS lights were on long before MAF failure though)

Diagnostic: I check the engine code and it says P103. Reading MAF value at idle is around ~2.0. With slight gas, it goes to ~48.0 and stays there no matter how much additional gas I give.

And MAF quickly drops to ~2.0 only when let go of gas pedal.


1. I clean the sensor with ethan alcohol and it's the same thing. The censor itself looks pretty clean visually. Does this all lead to bad MAF sensor? I live in ASIA and ordering part will take long time and I would like to make sure it's MAF, not any others before I order it.

2. I may have to drive the car before fixing it. Do you think it's really bad idea? Like, it will damage the car? If it just uses fuels inefficiently, I may do so until I fix it.

Thank you very much.


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P0103 Mass Air Flow Sensor - Above Limit

Possible fault cause

- Intake air system on pressure side (between turbocharger and engine) leaks

- Short circuit to B+

- Mass air flow sensor faulty

- Throttle jacking unit faulty

It is safe to drive the car as long as the CEL is NOT flashing.

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Thanks Loren,

I searched what P103 means on the forum and got what you listed.

I was hoping to narrow it down.. hmm...

I guess I have to check each of the possiblities.

So what do these two mean and how do I check them?

1. Short circuit to B+

2. Throttle jacking unit faulty

I appreciate for your help.

Edited by chrisk
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- Connect special tool 9637 to wiring harness (DME control module plug).

- Measure voltage between special tool 9637 pin III/23 and ground.

- Switch on the ignition.

Voltage should be 9 volts.

- Check voltage signal from MAF sensor with ’Ignition on’ (with Porsche System Tester 2 in the’Actual values/mass air flow’ menu, or with a voltmeter and special tool 9637).

Voltage should be 0.9 to 1.1 volts.

- Start the engine.

Voltage should be 1.2 to 1.5 volts at idle.


- Read out throttle actual value at idling speed (engine at operating temperature, air conditioning switched off).

Should be less than 4 %.

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Where are you located? Someone with a PTS2 or a durametric can check and clear the ABS and PSM lights.

Also, notice you are posted in the Top Issue section, so you won't get as much help here as in the regular boxster section.

Welcome to the neighborhood, Chuck

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I would check eBay for a used Duramatric cable, or you can order one from:


Being overseas there may be other options, but ibuying a durametric cable is worth every penny. I bought a used one from eBay, with it and a Bently's manual, there is nothing that I won't tackle.

There are many different OBD2 readers, but they won't talk to anything other than the emmissions and the engine computer.

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