1996 GMC Sierra 1500 P0174, P0171,P0154, AND P0122

Sometimes this is NOT a O/2 sensor issue ,,,,,If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replace the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced.
The P0171 code could also be caused may be caused by one or more of the following: debris on MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure or Engine Control Temperature (ECT) Sensor reading inaccurate,,,,,

P0171 possible cheap fix

P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)
P0154 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)
P0134 02 Sensor Circuit No Activity Detected (Bank I Sensor 1)

YO HAVE A VACUM LEAK AT INTAKE MANIFOLD GASKET OR HOSES THATS YOUR PROBLEM USE A CAN OF CARB CLEANER TO HELP FIND LEAK BY SPAING ARROUND INTAKE OK HOPE THIS HELPS BUT IM SHORE THATS YOUR PROBLEM RESON YOU REPLACE YOUR FUEL PRESSURE REGULATOR LEFT INTAKE LOSE OR PINCHED GASKETS OR LOSE HOSES TRY THAT OK

yes fix the skip first this can cause a lean code also look for any vacuum leaks

Check for vacuum leaks to start. Then check the evap system. I just replaced a evap vent solenoid on a suburban with the same codes. fixed the problem.

Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is generally the side of the engine that doesn't have cylinder #1.

Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.

Symptoms: You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.

Causes: A code P0174 may mean that one or more of the following has happened:
* The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
* There could be a vacuum leak downstream of the MAF sensor.


Possible solutions include:
* In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
* Inspect all vacuum and PCV hoses, replace if necessary
* Check for a dirty fuel filter and proper fuel pressure


Hope this helps (remember to rate this answer).

probably changed the wrong sensors
The units you should have replaced are the heated oxygen sensors in the exhaust manifold before the cat converters (HO2S)
oxygen sensors(O2S ) are after the cat converters codes p 0171,0174 are lean mixture codes and p 150,p0154 are HO2S sensor faults
as the Ho2s sensors read the composition of the exhaust gas and report to the ECM to adjust the fuel settings then t faulty HO2S sensors will result in a lean or rich reading resulting in the other codes

P0171 indicates a lean condition. The most common cause of this is a defective mass air flow sensor. Also check if any vacuum leaks. P0174 OBD-II Trouble Code

Technical Description

System Too Lean (Bank 2)

What does that mean?

Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust.

Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.

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Thanks.

The easyiest way is to go to alldatadiy.com and look at it there.