97 Merury Sable 6 cyl DOHC just started showing service engine light and local Autozone read P0171, P0174, P0402, and P1401. Just replaced EGR valve, sensor, solenoid 3 yrs ago. If MAF goes (171/174), can it cause the EGR codes (402,1401) as downstream impact?
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1997 Mercury Sable Question: IF MAF is causing P0171/P0174 can that trigger P0402/P1401 EGR codes?
Answer #1dandd August 25, 2011, 10:38Master
The P0402 is an excessive EGR flow code. I would re-inspect the operation of the EGR components. NO, a Mass Air Flow sensor will not cause the EGR codes, but be sure to check all these things before you buy a Mass Air Flow Sensor or have a good shop do so. You may have a leaking intake manifold etc.