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EricFromCT, Ford Technician
Category: Ford
Satisfied Customers: 3860
Experience:  20 years dealership exp., ASE A1-A9 L1 L2, Ford Lincoln Mercury Senior Master, Diesel Certified
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Have a 2002 ford f150 4x4 5.4. Can an exhaust leak cause a

Customer Question

Have a 2002 ford f150 4x4 5.4. Can an exhaust leak cause a check engine light code PO171?
Submitted: 1 year ago.
Category: Ford
Expert:  EricFromCT replied 1 year ago.

If the exhaust leak is bad enough it can cause p0171. Usually only a bad manifold leak will cause that. MOre common is a vacuum leak or low fuel pressure that causes p0171.

Customer: replied 1 year ago.
I thought it would be O2 sensor?
Expert:  EricFromCT replied 1 year ago.

02 sensors usually do not set a p0171. They usually set a lack of 02 switching code.