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Discussion Starter #1 (Edited)
First off, I want to thank the individuals that provided me with the information on how to change O2 sensors. Now the scenario. My check engine light came on awhile ago and I change the front two sensors last week. Well, driving how today the check engine light came back on.

It reads

DTC P0174
System Too Lean
(Bank 2)

I know what it means when it's running too lean. This means it's still an O2 sensor, right? Which one is it?

Thanks
 

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I suggest performing a search on this code, as it's posted about several times in the past.

From the following list, it's not necessarily an oxygen sensor (from the 1996 PC/ED Manual):

H41 DTCs P0172, P0174, P0171 AND P0175: FUEL SYSTEM AT THE CORRECTED ADAPTIVE LIMITS
Diagnostic Trouble Codes (DTCs) P0171 bank (1) (cylinder #1) and DTC P0174 bank (2) indicate the fuel/air ratio is too lean. The fuel adaptive system is at the rich correction limit.

DTC P0172 bank (1) and DTC P0175 bank (2) indicate the fuel/air ratio is too rich. The fuel adaptive system is at the lean correction limit.

DTCs HO2S Reference list:

HO2S-11 = DTCs P0171 and P0172
HO2S-21 = DTCs P0174 and P0175

Possible causes:

Fuel system

Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator.
Low fuel pressure.
Contaminated injector(s)
Induction system

Air leaks after the MAF.
Vacuum leaks.
Restricted air inlet.
PCV system.
Fuel purge system.
Improperly seated dip stick.
EGR

Leaking gasket.
Stuck open EGR valve.
Leaking diaphragm.
Base engine

Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2S's.
Check air intake for leaks, obstructions and damage.
Check air filter, air filter housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.
 

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check on the passenger side of your car at the back of the intake..
there is a hose that runs under the intake from the pcv valve to the plenum. mine had rotted and was providing a lean/rich condition for both sides.
just a thought
 
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