| Technical Service Bulletin | Group
ENGINE ELECTRICAL | |||
| Number
04-36-020 | ||||
| Subject
2001 – 2005 XG300/350 P0171, P0174 (SYSTEM TOO LEAN BANK 1/BANK 2) | Date
DECEMBER, 2004 | |||
| Model
2001 – 2005 XG300/350 | ||||
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.
| Condition | Key On and the Engine turned OFF | At Idle in Park | At 2,500 in Park | Under Load at Wide Open Throttle, while driving the vehicle |
| Mass Air Flow Value | 1,000mv +/- 50mv | 1,400mv +/- 50mv | 1,900mv +/- 50mv | 4 volts
(minimum) |
- 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:
| MODEL | MASS AIRFLOW SENSOR PART NUMBER |
| XG300 | 28100-39000 |
| XG350 – with production dates between 09-01-2001 and 11-26-2001. | 28100-39400 |
| XG350 with a production date after 11-26-2001. | 28100-39450 |
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.
- UL certified product designed to safely and accurately troubleshoot a variety of automotive and household electrical problems
- Auto-ranging scales automatically selects correct measurement range and eliminate the need to dial in the correct range when making electronic measurements
- Features large digital display and color coded LED's to easily check the charge status of batteries
- Single-setting resistance function for AC and DC voltage
- 10 MegOhm input impedance; safe for electrical and automotive use; prevents damage to the vehicle’s ECU
Last update on 2026-06-16 / Affiliate links / Images from Amazon Product Advertising API
- Your unit is calibrated prior to shipment with a new nist-traceable calibration Certificate with data
- The NIST calibration provides you assurance your instrument Meets manufacturer’s specifications. Your instrument is ready to Use day one meeting most quality system standards
- Highly visible LED screen with white back light
- Ergonomically designed compact size provides easy one-handed operation
- Ideal for Commercial applications that require demanding settings
Last update on 2026-06-16 / Affiliate links / Images from Amazon Product Advertising API
Last update on 2026-06-16 / Affiliate links / Images from Amazon Product Advertising API
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