P0137 o2 circuit low voltage bank 1 sensor 2 --o2 sensor after the cat converter -check for faulty o2 sensor -short or open circuit exhaust leak near sensor or plugged cat converter ----P0171 and P0174 -system too lean bank 1--and system too lean bank 2 they are usually from the same problem which can be caused from the o2 problem but check ur maf sensor connections and or clean if necessary[carb cleaner] vacuum leak downstream from maf sensor also inspect pcv lines
SOURCE: p0171 and p0174 codes
P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)
If a car has a check engine light on and has P0171 and P0174 codes stored, the most likely cause is a vacuum leak. These codes are set by the car’s computer when it sees too much oxygen in the exhaust. Excessive oxygen readings in the exhaust will set lean codes. This does not mean that the oxygen sensors are defective. It is a common mistake for people to replace oxygen sensors when lean codes are present. Just because the code is related to oxygen sensor readings, it doesn’t mean that the oxygen sensors are bad. If both of these codes are stored this means that both banks of the engine have excessive oxygen in the exhaust. If the oxygen sensors are replaced it’s most likely that the same codes will reappear. It is very uncommon for two oxygen sensors to fail at the same time.
Therefore the most likely cause of P0171 and P0174 codes is a vacuum leak. The source of a vacuum leak can be one of many things. The most common cause of a vacuum leak is a leaky hose. Vacuum hoses over time can become dry and brittle. The rubber deteriorates and can leak causing a vacuum loss. Many times a leaky vacuum hose can be found by listening for a hissing sound. A large vacuum leak can even make the car run rough at idle. In some cases it will not idle without feathering the gas pedal.
SOURCE: OBD codes P0171 and P0174
Look on the passenger side of the intake at the rubber elbow attached to the big black plastic tube and then to the intake manifold. Make sure it is not sucking shut and maybe a small hole in the bottom of it.
SOURCE: poor idle dtc P1151, P1131,P0174, P0171. runs ok
Change plugs, and Mass Air Flow sensor. This should do the trick
SOURCE: 1999 ford taurus emission reading p0171 and p0174
just tune up ur car periodicly, clean filter. clean ur sparkplug.
SOURCE: codes P0171, P0174, P0440
This is usually an oxygen sensor, replace the O2 sensor located above the catalytic converter before replacing the evaporator purge canister.
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