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Richard, ASE Certified Technician
Category: Ford
Satisfied Customers: 15545
Experience:  12 years at a Ford Lincoln/Mercury and Jaguar dealer as a technician and shop foreman.
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What is causing p1131 and p1151 codes in a 2002 f150

Customer Question

What is causing p1131 and p1151 codes in a 2002 f150
Submitted: 8 years ago.
Category: Ford
Expert:  Richard replied 8 years ago.

Hello and welcome to


DTCP1131 and P1151 are O2 sensors lack of switching reading lean. This is do to a lean running engine most likle from a vaccum leak. You should inspect the pcv tube abd elbow as they usually coolapse and leak. It may also be from lack of fuel from a partially clogged filter. Hope this helps.

Customer: replied 8 years ago.

I have checked for leaks with smoke machine and couldn't find any, i replaced fuel filter already...I have read and been told that it could be an intake isolator bolt leak, but i've also read of someone replacing those when having problems with these codes and that did not solve problem, do you think it is possible the Mass airflow sensor needs cleaning, or could the fuel pump be malfunctioning or maybe restriction in the fuel lines? If so what should i proceed with first?

Expert:  Richard replied 8 years ago.
On the 4.2 V6 the intake gasket and the isolator bolts are notorious for leaking causing those codes. I would start there first.