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.