What can cause P0171 but O2 sensor 1 has high volts when unplugged?

Tiny
HASS2B
  • 2003 SUBARU WRX
  • 75,000 MILES

I have a 2003 subaru impreza wrx. Recently it has started running really bad and the P0171 code was on along with the P0031. I replaced both 02 sensors, fuel filter, cleaned the MAF sensor. The only code showing now is P0171 which means it is running lean but the voltage of o2 sensor 1 bank 1 is really high around 3.7 V. The car runs a little better but still hesitates when trying to get up to speed. I have no idea what could be causing it.

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Sunday, April 1st, 2012 AT 3:47 PM

1 Reply

Tiny
ASEMASTER6371
  • EXPERT
  • 25,554 POSTS

171 is a vacuum leak. It could be a bad hose, mass air flow, pcv valve, low fuel pressure or the big air hose to the throttle body has a hole in it.

Roy

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Sunday, April 1st, 2012 AT 5:02 PM

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