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I have an 02 Navigator that is running rough at idle (I have seen several posts about similar issues)
I went to Autozone and was given the following Codes
P0171
P0174
P1152
P1151
P1131
All seem to indicate the engine is running too lean.
Where shoulf I begin?
replace Fule filter?
O2 sensor?
Mass Air Flow sensor?
Other suggestions?
Very carefully inspect all of the vacuum and intake hoses including the PCV system. A leak will set off these codes. Sometimes you can hear the leak if you listen carefully.
This is very common and replacing parts like the HEGO sensors, MAF sensors, and PCM will not fix it.