Engine Controls - DTC P0101 Stored
01 07 46May 7, 2007
2010352 Supersedes T.B. Group 01 number 05-11 dated July 21, 2005 due to inclusion into ElsaWeb.
Affected Vehicles
Condition
DTC P0101 (16485) Stored in DTC Memory
Diagnostic Trouble Code (DTC) P0101 (16485) Stored in DTC memory.
Technical Background
Diagnostic aid for finding other Mass Air Flow (MAF) -G70- fault causes.
Production Solution
No production change required.
Service
DO NOT automatically replace the Mass Air Flow (MAF) sensor -G70- for this condition, first perform the following:
^ Repair any other DTCs stored in electronic diesel control module.
WARNING:
VAS 5051/5052 must be secured to the rear seat and operated from there by a second person.
Procedure
^ Warm up engine to above 85�C (185�F)
^ View Measuring Value Block (MVB) 93, channel 2 in deceleration mode from approximately 2300 RPM to 1800 RPM in 5th gear (manual or Tiptronic).
Deceleration is indicated when channel 1 looks as follows: 00000100.
Desired value for channel 2 = 0.95 1.05.
Tip:
3rd or 4th gear may be used if 5th gear operation causes road speed higher then the local speed limit. Take an average of MVB93, channel 2 value. This value can be used to determined if changes made during the repair have been beneficial.
^ Inspect for leaks in induction system before and after turbocharger including intake manifold.
KLI9210 may be used to smoke check the induction system as follows:
^ Disconnect hose from MAF sensor and connect adapter 1687/50B to intake tube at MAF sensor.
^ Plug crankcase breather hose with 1687/50A.
^ Connect KLI9210 pressure hose to 1687/50B adapter at MAF sensor and follow general set up instructions for smoke generator.
^ Fill induction system with smoke for 2 minutes and check for smoke escaping.
Tip:
A very small leak may be present at the clamped connection shown in illustration 20-A188 (black arrow). If there is no damage to the hose or pipe, and the clamp is installed correctly, no further action is needed. A very small leak at this point will not have any influence.
^ Check intake air temperature sensor -G72- plausibility. Ignition ON, engine OFF: MVB 7, channel 3.
Temperature should correspond approximately to ambient temperature with a cold engine. Repair if out of normal range.
^ Compare Charge Air Pressure sensor -G31- and barometric pressure. Ignition ON, engine OFF.
MVB 10, channels 2 (barometric pressure) & 3 (charge air) should be similar as well as corresponded to actual altitude. Sea level = approx. 1000 mbar.
Tip:
If intake air reading in preceding step deviates from the true temperature, then the barometric reading will also be incorrect. Repair as needed.
^ With the engine running, view MVB 3, channel 3 while gently wiggling MAF sensor -G70- connector.
If valve changes abruptly:
^ Check and/or replace MAF sensor wiring terminals if necessary.
^ Remove EGR valve and inspect if valve is stuck open.
^ Check Camshaft/Crankshaft timing at idle using MVB 4, channel 4.
Correct range = approximately 0 - 2.
If out of range:
^ Adjust using procedure in ElsaWeb.
If cause is still not found:
^ Proceed to remaining items outlined in table of possible causes.
Quality Check
^ Evaluate MVB 93 while performing deceleration phase as previously described.
^ On Vehicle Diagnostic, testing and information system VAS 5051/5052, select "Guided Functions".
^ Select "BEW engine".
^ Select "Generate readiness code"
Warranty
*Code per warranty vendor code policy.
Required Parts and Tools
No Special Parts required.
No Special Tools required.
Additional Information
All part and service references provided in this Technical Bulletin are subject to change and/or removal. Always check with your Parts Dept. and Repair Manual's for the latest information.