Find out from customer what type fuel their using, ethanol as become a culprit for this
code on non flex fuel cars, found out after days of troubleshooting, if they are using e85
and the car is not designed for flex fuel this could be a problem.

That code just mean the o2 sensor 1/1 reads a lean exhaust. A low fuel presure will
also set code p0174 for 2/1 sensor. Many things can cause this code to set. There is
no one answer to this issue. You must follow the diagnosis procedure shown in your
shop repair manual. Ondemand5,alldata. Possible causes will be o2 sensor,
wiring,pcm,engine mechanical,fuel delivery ,ect sensor or wiring,map sensor or wiring
and or exhaust leak. The first thing I will do is swap sensors if problem changes
places you know is a sensor problem, if not more testing is needed, check all wiring
and connectors, make sure there is no exhaust leak before the sensor, good luck.

Yes buddy your right too, ethanol is causing all kinds of issue