P1128 engine lean code for 2000 Volkswagen Cabrio with 2.0L engine

Question:

This vehicle has this code P1128-bank1 lean code. I have tested the engine for vacuum leak using ATS tips and no leak was found. Using my fuel pressure gage the fuel pump pressure was also checked OK. I also did a quick tune up like changing the spark plugs, wires and fuel filter to no avail. In your ATS tips, you mentioned the failure of mass sensor causing this, is this the case here?

ATS Advisor:

You are correct to suspect the mass sensor is the culprit. As a matter of fact you can call the dealer and you will find they stock it a lot. The sensor fails because of oil contamination being induced in the intake. Don't even bother cleaning it but replace it.

Tips:
Once the mass sensor is replace, reset the code by touching both batt together for a few minutes.

While you are at it, replace your pcv valve to prevent contamination.