XG 350 V6-3.5L (2002)
Air Flow Meter/Sensor: Customer Interest
Engine Controls - DTC's P0171/P0174 Stored in Memory
Group: ENGINE ELECTRICAL
Number: 04-36-020
Date: DECEMBER, 2004
Model: 2001 - 2005 XG300/350
Subject
2001 - 2005 XG300/350 P0171, P0174 (SYSTEM TOO LEAN BANK 1/BANK 2)
DESCRIPTION:
If a 2001 XG300 or 2002 - 2005 XG350 sets codes P0171 and or P0174 (Hi-Scan Pro description is: "System too Lean Bank 1/ System too Lean Bank
2"), perform the following test procedure to correctly diagnose this condition:
Using the Hi-Scan Pro (under the current data menu), record the Long Term Fuel Trim for Bank 1 and Bank 2 at idle and at 2,500 rpm. If both B1 and
B2 have a positive Long Term Fuel Trim Reading greater than 10%, perform the following test procedure:
Using the Hi-Scan Pro, record the Mass Airflow sensor values under the different parameters shown in the table below. The engine must be at operating
temperature with the Air Conditioning turned OFF and there cannot be an exhaust hose over the tail pipe.
1.
If the Mass Airflow values do not meet the criteria above:
^
Verify that there is a constant 5 volt reference and ground to the Mass Airflow sensor. (See the MFI control section in the appropriate
Electronic Trouble Shooting manual)
If the 5 volt reference and ground are within specification, confirm fuel pressure is between 35 - 39 psi at idle with fuel pressure regulator hose
connected and between 44 - 48 psi with the regulator vacuum line disconnected.
If the 5 volt reference, ground, and fuel pressure are within specification, replace the Mass Airflow sensor.
PARTS INFORMATION:
Confirm that the vehicle is repaired by rechecking the Long Term Fuel Trim at idle and at 2,500 rpm after a 10-15 minute test drive.
WARRANTY INFORMATION:
Normal warranty operation codes and times apply.
