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eauto
eauto, The Car Guy
Category: VW
Satisfied Customers: 15062
Experience:  ase certified tech
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My name is ***** *****. I have a 2007 VW New Beetle

Customer Question

Hello. My name is ***** *****. I have a 2007 VW New Beetle with the 2.5L (BPR) engine and I keep getting the fault code P0171. Can you help?
JA: Thanks. Can you give me any more details about your issue?
Customer: Yes Check engine light comes on. The only fault code is the P0171 fault code. Long term fuel trim stays at about 20%. Fault usually occurs under moderate load and around 30 miles per hour. Smoke tested intake system and no leaks were found. Measured crankcase vacuum with vacuum gauge connected to oil dipstick tube and it reads just near 0"hg. Cleaned mass airflow sensor and fault still returns
JA: OK got it. Last thing — VW Mechanics generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 7 months ago.
Category: VW
Customer: replied 7 months ago.
Are there VW mechanics on staff today or will I have to wait until Monday?
Expert:  eauto replied 7 months ago.
can you try a new maf? they are usually the causse
Customer: replied 7 months ago.
I have a few questions on that. How is the mass airflow failing to produce this fault code? I ask this because I am getting a reading of 2.5-3.5 grams/second from my MAF at idle and as the load increases, so does the reading accordingly.
Customer: replied 7 months ago.
My second question is, did VW come out with an updated MAF that is better than the one that came in it? The vehicle has never had one...
Expert:  eauto replied 7 months ago.
that's in range is the idle normal?
Customer: replied 7 months ago.
Yes. The idle is normal. Overall, the car does not have any driveability issues.
Customer: replied 7 months ago.
The only thing that is not normal is the long term fuel trim being so high. All smoke tests that I have done come back showing there are no leaks.
Expert:  eauto replied 7 months ago.
A dirty or faulty MAF sensor can also cause positive fuel trim numbers because it “under-reports” airflow, driving the base air/fuel calculation lean.
Expert:  eauto replied 7 months ago.
Unmeasured air is reaching the combustion chambers.Less than the commanded amount of fuel is reaching the combustion chambersOne or more sensors is reporting incorrectly.
Customer: replied 7 months ago.
I have cleaned the mass airflow sensor hot wires with CRC Mass Airflow cleaner. Also I have a K and N filter installed (for about 3 years now; clean it regularly with every oil change with the K and N cleaning kit). I measured the fuel pressure at idle and at 2000 RPM and its roughly 50PSI
Customer: replied 7 months ago.
If I replace the MAF, is the VW MAF the preferred choice or can I use an aftermarket MAF?
Expert:  eauto replied 7 months ago.
factory is always preference...but if the price difference is huge u an try aftermarket think oe is 285
Customer: replied 7 months ago.
Ok. Hypothetically, if the new MAF doesn't fix it, where would I go from there?
Expert:  eauto replied 7 months ago.
double check for umetered air leak re smoke test

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