I have a 1998 Ford Contour that has a check engine light. I checked the codes, and found:

  • P0171 System Too Lean (Bank 1)
  • P0174 System Too Lean (Bank 2)
  • P0401 Insufficient EGR Flow
  • P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1

I think the main culprit might be a vacuum leak, and that the codes are related to the side effects caused by the leak. Are there any common hoses that I should check first? I remember we had two main hoses on BMWs that were usually the guilty party.

  • Checked for leaks, and found none. I did find that the fuel pump might not be coming on. Dec 23 '11 at 15:01

The problem did end up being the fuel pump. Checked wires and fuses, but in the end it was a bad pump. The filter was also replaced, and can probably be blamed for the pump failing.

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