Hi. All,
After a long time I am getting the same P0174 Fuel Trim System Lean Bank 2 code. This code had gone away after three fuel treatments. But now it came back on. Here are the details from the program AutoTap that I ran today.
This is from the confirmed code data:
--------: FREEZE FRAME DATA :--------
Generated by DTC code: P0174
Fuel System Status Bank 1: CL-1
Calculated Engine Load: 33.3 %
Engine Coolant Temperature: 194 °F
Short Term Fuel Trim Bank 1: 10.9 %
Long Term Fuel Trim Bank 1: 19.5 %
Short Term Fuel Trim Bank 2: 10.2 %
Long Term Fuel Trim Bank 2: 19.5 %
Engine Speed: 2355 RPM
Intake Air Temperature: 70 °F
Mass Air Flow Rate: 4.095 lb/min
Throttle Position Angle: 16.1 %

This is other data during the test:

AutoTap Diagnostic - Version 3.10
Date: 1/3/2010 1:20:56 PM
Hardware Serial: 0101082008
Check Engine Light: ON
Time Since Codes Cleared: ---
Distance Since Codes Cleared: ---
Drive Cycles Since Codes Cleared: ---
Confirmed Diagnostic Trouble Codes:
Code: Description:
P0174 Fuel Trim System Lean Bank 2
Possible Diagnostic Trouble Codes:
Code: Description:
P0171 Fuel Trim System Lean Bank 1
P1111 IAT Circuit Intermittent High Voltage
--------: EMISSION TEST STATUS :--------
Emission Status: Fail
Vehicle Model Year: 2003
OBD Compliant: Yes
Misfire Monitoring: Complete
Heated Catalyst Monitoring: NotSupported
Comprehensive Component Monitoring: Complete
Catalyst Monitoring: Complete
Fuel System Monitoring: Complete
Evaporative System Monitoring: Complete
Secondary Air System Monitoring: NotSupported
EGR System Monitoring: NotSupported
Oxygen Sensor Monitoring: Complete
Oxygen Sensor Heater Monitoring: Complete
A/C System Refrigerant Monitoring: NotSupported

My mechanic tell me that this is nothing to worry about and will requrie many test and trial and error to figure out this cause that creates this error. Do you all agree? Shall I just turn off the worror code and keep driving? I would think that there has to be a solution to this. I am not losing any performance or reduced milage/efficiency. The car does drives and purrs like a cat.
Please assist/advise if possible.

Thanks.

 

These codes are usually associated with a dirty or defective MAF sensor or in my case a vacuum leak. Try to clean the MAF sensor with the correct cleaner for this application and check for vacuum leaks.

 

your short and long term fuel trim show a vacuum leak, BUT if these were not cleared after you do work you can be fighting a no onger existant problem that long term fuel trims in the ecu is trying to fix. short term shows 10% added fuel and long terms are almost maxed at 19%. do a hard system reset with the battery, disconnect negative terminal from battery and touch to still connected postive post. NO it does nothing more than drain capacitors to erase volatile memories in ecus that retain things like long term fuel trim. if you can montior short term fuel trims with your scanner this is the best way to look for leak with brake clean, car clean etc.... as you spray suspected areas look for an increase in short term trims. especially look for deterioration of the air intake tube at the bellows. Now that ive said all this like JOJO said this code on your car is usually created by a mass air flow sensor fault. your grams/sec (converted to what I see everyday, I dont use #/min) is 31gms/sec and I dont know if that okay at 2300rpm, but it should be 5-7gms/sec@idle. clean it and try again if you find no vacuum leaks, and cleaning results in a reoccurance of cel then replace the MAFS...oh and get a different mechanic that knows more about advanced engine/drivabilty diag. because the short /long term trims tell all

 

Hi. All,
THanks for the responses and advise.
It appears that the entire problem was caused by a faulty fuel pump. After it was replaced, the car purrs and runs like a charm. It has been two weeks since that replacement and everything seems fine....for now.
Abe