Audi Repair: 1999 Audi A6 error P1136 & P1138, mass air sensor, audi a6 quattro

Question
Greg:

I have a 1999 Audi A6 Quattro 2.8 with 106k miles. I am getting error codes P1136 and P1138. I have already replaced the Mass Air Sensor.  This weekend, I am going to replace the small vacuum lines (with mesh wrapping around the hose) near the air intake of the engine.  Is there anything else you can think of that would cause these errors?  (oxygen sensors?).

Your advice is much appreciated.

Craig

Answer
Hello
If you replace mas air flow already, you must have vacuum leak. check and replace all broken hoses(just like your said) Most of the time they brake on the secondary air valves in the back of cylinder heads.. these faults come only on vacuum leaks or bad mas air flow.
good luck . Greg