Ford Repair Questions? Ask a Mechanic for Answers ASAP
Note: Before servicing DTCs P0171, P0172, P0174 and P0175, verify with the customer that before the "Check Engine Light" came on, the vehicle did not run out of fuel.
Diagnostic Trouble Codes (DTCs) P1131 and P1151 indicate the system is correcting rich for an overly lean condition. The HO2S voltage is less than 0.45 volt.
DTCs P1132 and P1152 indicate the system is correcting lean for an overly rich condition. The HO2S voltage is greater than 0.45 volt.
DTCs P1130 and P1150 indicate the fuel control system has reached its maximum compensation for a lean or rich condition and HO2S is not switching.
DTC P0171, left bank, and DTC P0174, right bank, indicate the fuel/air ratio is too lean. The system is at the XXXXX XXXXXmit.
DTC P0172, left bank, and DTC P0175, right bank, indicate the fuel/air ratio is too rich. The system is at the lean limit.
DTC/HO2S Reference List
The most likely cause of these lean concerns are PCV or vacuum hose leaks or the intake gaskets and isolator bolts are leaking. You codes mean the left and right bank O2's are detecting lean and they are telling the computer to add more fuel. Lean concerns are normally always caused by an air leak after the MAF sensor. An air leak would be a vacuum leak since the intake is sucking air from the air filter and if there is a leak it is getting more than than the MAF detected entering the engine