Contour Enthusiasts Group Archives Forums General Troubleshooting "System Too Lean (bank 2)"

Hi, everybody:

I have a 98 Contour with 2.5 L 6 cylinder (Duratec) at about 65000 miles. The Check Engine lamp has been on for > 4 weeks. I checked it with an OBD II scanner, and found the diagnostic trouble code "P0174", with a description of "System Too Lean (bank 2)" I suspect the Oxygen sensor in bank 2 is bad. Anyone had the similar experience and know how to fix it?

Specifically, is bank 2 opn the front (radiator) side? Murray's price for O2 sensor (bank 1) is $60. Is it a difficult job to get it replaced? Does it require special tools? How to ensure the sensor is rewired correctly?

Thanks!!!!!!

Welcome. . P0174 is more of a vacuum leak. Not a O2 sensor problem. Try some of these suggestions first. Bank 2 is the radiator side.

From TSB,
P0174 - System Too Lean (Bank 2) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The code is set when the adaptive fuel tables reach a rich calibrated limit. Fuel System:
�· Contaminated fuel injectors
�· Low fuel pressure or running out of fuel (fuel pump, filter, fuel supply line restrictions)
�· Vapor recovery system (VMV)
Induction System:
�· MAF contamination
�· Air leaks between the MAF and throttle body
�· Vacuum leaks
�· PCV system concern
�· Improperly seated engine oil dipstick
EGR System:
�· Leaking gasket
�· Stuck EGR valve
�· Leaking diaphragm or EVR
Base Engine:
�· Exhaust leaks before or near the HO2S
�· Secondary air concern
Powertrain Control System:
�· PCM concern

Thanks, Tony2005! You listed several possible reasons for the P0174 code. I do have the fuel filter listed by a dealer as "need to be replaced". Maybe I need to replace that to see the lamp turns off. By the way, what is TSB, and how to accesss it?

Thanks!

Huacat

TSB Technical Service Bulletin. Need to pay a yearly fee to get from alldata.com or something like that. Quite a few are accessible from the internet. Yes, change the fuel filter and see if it helps.

TSB
http://www.v8sho.com/SHO/TSB0197HO2SServiceTips.htm

Fuel filter.
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=v6maint&Number=958655&page=0&view=collapsed&sb=5&o=186&fpart=1